Promoting cancer control training in resource limited environments: Lagos, Nigeria.

In resource limited nations, cancer control is often a lower priority issue creating challenges for the prevention, early diagnosis, and treatment of cancer. Training and education are vital components of efforts to tackle this problem. A 3-day cancer control workshop was conducted at the Lagos State University Teaching Hospital (LASUTH), Nigeria, in 2013. The curriculum included didactic lectures, panel discussions, and interactive sessions on local cancer statistics, preventive strategies, cancer registries, screening and diagnostic options, and treatment approaches with limited resources (chemotherapy, radiotherapy, surgery, and palliative care) and several site-specific (breast, lung, cervical, prostate, and colon) topics. Pre-workshop and post-workshop questionnaires were completed by participants. Eighty-six percent of the 50 workshop participants completed at least one questionnaire. Participants were mainly nurses and physicians (89% of responders), and 40% reported >25 years of practice experience. The more common local needs identified were professional education (65%) and increasing public cancer awareness (63%). The greatest interest for future programs was on research collaborations (70%). An immediate impact of the workshop was the commencement of monthly tumor board conferences and a review of the current cancer registry data. Capacity building is critical for the execution of effective cancer control strategies. Conducting collaborative workshops represents a cost-effective means of launching programs and energizing the medical community to pursue ongoing education and research addressing the anticipated cancer epidemic on the African continent.

Large residual strains are present in the intervertebral disc annulus fibrosus in the unloaded state.

The intervertebral disc annulus fibrosus (AF) is subjected to high circumferential tensile stresses resulting from nucleus pulposus pressurisation under axial compression. In other pressure containing tissues, such as blood vessel walls, residual compressive stresses along the inside surface of the tissues without pressurisation reduce peak tensile stresses under pressurisation. This study hypothesised that similar patterns of residual stress exist in the annulus fibrosus. Accurate characterisation of residual stresses is essential for both the incorporation of nonlinear material descriptions into models of the disc as well as the design of effective annulus repair strategies. By imaging nine bovine caudal discs before and after the release of residual stresses via incision, we measured a mean residual stretch of 0.86 ± 0.13 at the inner AF and 1.02 ± 0.08 at the outer AF. These stretch values were used to calculate a gradient of residual stress ranging from -230 ± 22 kPa of compression at the inner AF to 54 ± 0.2 kPa of tension at the outer AF. Material models of AF have assumed that the AF was in a stress free reference state when there are no external loads. However, this study documents that there are large residual stresses in the AF even without external loads. The release of residual tension in the outer AF by herniation, needle injection or incisions makes closure difficult and may accelerate degeneration of the surrounding tissue. Retention of these residual stresses may be essential to maintaining disc mechanical function and to producing viable AF repair techniques.

Complex loading affects intervertebral disc mechanics and biology.

BACKGROUND: Complex loading develops in multiple spinal motions and in the case of hyperflexion is known to cause intervertebral disc (IVD) injury. Few studies have examined the interacting biologic and structural alterations associated with potentially injurious complex loading, which may be an important contributor to chronic progressive degeneration. OBJECTIVE: This study tested the hypothesis that low magnitudes of axial compression loading applied asymmetrically can induce IVD injury affecting cellular and structural responses in a large animal IVD ex-vivo model. METHODS: Bovine caudal IVDs were assigned to either a control or wedge group (15°) and placed in organ culture for 7 days under static 0.2MPa load. IVD tissue and cellular responses were assessed through confined compression, qRT-PCR, histology and structural and compositional measurements, including Western blot for aggrecan degradation products. RESULTS: Complex loading via asymmetric compression induced cell death, an increase in caspase-3 staining (apoptosis), a loss of aggrecan and an increase in aggregate modulus in the concave annulus fibrosis. While an up-regulation of MMP-1, ADAMTS4, IL-1ß, and IL-6 mRNA, and a reduced aggregate modulus were induced in the convex annulus. CONCLUSION: Asymmetric compression had direct deleterious effects on both tissue and cells, suggesting an injurious loading regime that could lead to a degenerative cascade, including cell death, the production of inflammatory mediators, and a shift towards catabolism. This explant model is useful to assess how injurious mechanical loading affects the cellular response which may contribute to the progression of degenerative changes in large animal IVDs, and results suggest that interventions should address inflammation, apoptosis, and lamellar integrity.

Genipin-crosslinked fibrin hydrogels as a potential adhesive to augment intervertebral disc annulus repair.

Treatment of damaged intervertebral discs is a significant clinical problem and, despite advances in the repair and replacement of the nucleus pulposus, there are few effective strategies to restore defects in the annulus fibrosus. An annular repair material should meet three specifications: have a modulus similar to the native annulus tissue, support the growth of disc cells, and maintain adhesion to tissue under physiological strain levels. We hypothesized that a genipin crosslinked fibrin gel could meet these requirements. Our mechanical results showed that genipin crosslinked fibrin gels could be created with a modulus in the range of native annular tissue. We also demonstrated that this material is compatible with the in vitro growth of human disc cells, when genipin:fibrin ratios were 0.25:1 or less, although cell proliferation was slower and cell morphology more rounded than for fibrin alone. Finally, lap tests were performed to evaluate adhesion between fibrin gels and pieces of annular tissue. Specimens created without genipin had poor handling properties and readily delaminated, while genipin crosslinked fibrin gels remained adhered to the tissue pieces at strains exceeding physiological levels and failed at 15-30%. This study demonstrated that genipin crosslinked fibrin gels show promise as a gap-filling adhesive biomaterial with tunable material properties, yet the slow cell proliferation suggests this biomaterial may be best suited as a sealant for small annulus fibrosus defects or as an adhesive to augment large annulus repairs. Future studies will evaluate degradation rate, fatigue behaviors, and long-term biocompatibility.

Regional cancer control in south-eastern Nigeria: a proposal emanating from a UICC-sponsored workshop.

There is an impending cancer epidemic in Africa. In Nigeria, this disease is causing untold devastation, and control measures are desperately needed. Breast, cervical, prostate, and liver cancers are the most common types in Nigerian adults. In children, the predominant malignant diseases are Burkitt's lymphoma, acute lymphoblastic leukemia, neuroblastoma, and Wilm's tumor (nephroblastoma). The focus of efforts to control cancer in Nigeria should be directed at prevention with adequate attention to planning/policy making, early detection, accurate diagnosis, treatment and palliative care. National and regional allocation of sufficient resources is required, accompanied by measurable objectives and appropriate emphasis on accountability.

Localized Intervertebral Disc Injury Leads to Organ Level Changes in Structure, Cellularity, and Biosynthesis.

A literature review and new data are presented to evaluate the influence of intervertebral disc (IVD) injury on biomechanics, cellularity, inflammation, and biosynthesis. Literature and new experimental evidence support the hypothesis that localized injury in the disc can lead to immediate and long-term organ level changes in biomechanics and biology of the IVD. Biomechanical properties defining motion segment bending behaviors sensitive to injuries that affect anulus fibrosus (AF) integrity and nucleus pulposus (NP) pressurization. Axial mechanics and IVD height measurements show sensitivity to puncture and other injuries that reduce NP pressurization. Torsional biomechanics are strongly affected by the extent and location of AF lesions but are less sensitive to reduced NP pressurization. IVD injuries such as puncture and stab incisions may also lead to a cascade of biological changes consistent with degeneration, including loss of cellularity, altered biosynthesis and inflammation. New results on effects of 25G needle injection of saline into a bovine IVD organ culture model demonstrated a loss of cellularity and down-regulation of matrix gene expression, providing a specific example of how a minor injury affects the IVD organ response. We conclude that localized injuries in the IVD can induce an organ level degenerative cascade through biomechanical and biological mechanisms, and their interactions. Attempts at IVD repair should target the dual biomechanical roles of the anulus of maintaining nucleus pressurization and transmitting loads across the vertebrae. Biologically, it remains important to maintain IVD cellularity and biosynthesis rates following injury to prevent downstream degenerative changes.

Childhood leukaemia in Belarus, Russia, and Ukraine following the Chernobyl power station accident: results from an international collaborative population-based case-control study.

BACKGROUND: There is little evidence regarding the risk of leukaemia in children following exposure to radionuclides from the Chernobyl Nuclear Power Plant explosion on April 26, 1986. METHODS: This population-based case-control study investigated whether acute leukaemia is increased among children who were in utero or <6 years of age at the time of the Chernobyl accident. Confirmed cases of leukaemia diagnosed from April 26, 1986 through December 31, 2000 in contaminated regions of Belarus, Russia, and Ukraine were included. Two controls were matched to each case on sex, birth year, and residence. Accumulated absorbed radiation dose to the bone marrow was estimated for each subject. RESULTS: Median estimated radiation doses of participants were <10 mGy. A significant increase in leukaemia risk with increasing radiation dose to the bone marrow was found. This association was most evident in Ukraine, apparent (but not statistically significant) in Belarus, and not found in Russia. CONCLUSION: Taken at face value, these findings suggest that prolonged exposure to very low radiation doses may increase leukaemia risk as much as or even more than acute exposure. However the large and statistically significant dose-response might be accounted for, at least in part, by an overestimate of risk in Ukraine. Therefore, we conclude this study provides no convincing evidence of an increased risk of childhood leukaemia as a result of exposure to Chernobyl radiation, since it is unclear whether the results are due to a true radiation-related excess, a sampling-derived bias in Ukraine, or some combination thereof. However, the lack of significant dose-responses in Belarus and Russia also cannot convincingly rule out the possibility of an increase in leukaemia risk at low dose levels.

A prognostic model for prolonged event-free survival after autologous or allogeneic blood or marrow transplantation for relapsed and refractory Hodgkin's disease.

There are several prognostic models for Hodgkin's disease (HD) patients, but none evaluating patient characteristics at time of blood and marrow transplantation (BMT). We developed a prognostic model for event-free survival (EFS) post-BMT based on HD patient characteristics measured at the time of autologous (auto) or allogeneic (allo) BMT. Between 1/1991 and 12/2001, 64 relapsed or refractory HD patients received an auto (n=46) or allo (n=18) BMT. A multivariate prognostic model was developed measuring time to relapse, progression or death. Median follow-up was 51.7 months; median EFS for auto and allo BMT was 36 and 3 months, respectively (P=0.001). Significant multivariate predictors of shorter EFS were chemotherapy-resistant disease, KPS <90 and > or =3 chemotherapy regimens pre-BMT. Patients with two to three adverse factors had significantly shorter EFS at 2 years (58 vs 11% in auto; 38 vs 0% in allo BMT patients). Despite a selection bias favoring auto BMT, the model was valid in both auto and allo BMT groups. We were able to differentiate patients at high vs low risk for adverse outcomes post-BMT. This prognostic model may prove useful in predicting patient outcomes and identifying high-risk patients for novel treatment strategies. Validation of this model in a larger cohort of patients is warranted.

Exposure to Schistosoma mansoni infection in a rural area in Brazil. II: household risk factors.

A number of studies have pointed out the potential importance of the household in the transmission of schistosomiasis. The clustering of domestic activities associated with water collection, storage, and usage can result in the sharing of transmission sites and infective water contact behaviours. In this study, we employed a variance component method to estimate effects due to individual risk factors and shared residence on the variance in faecal egg counts during Schistosoma mansoni infection. A suite of covariates, which included demographic, socioeconomic, water supply, and water contact behaviour terms, contributed 15% to the variance in faecal egg counts. Shared residence alone accounted for 28% of the variance in faecal egg excretion. When both the suite of covariates and shared residence were considered in the same model, shared residence still contributed 22% to the variance in infection intensity. These results point to the importance of shared residence as a means of capturing the complex interrelationship between shared demographic, socioeconomic, physical environmental, and behavioural factors that influence transmission of schistosomiasis at the household level.

Perinatal factors and risk of neuroblastoma.

Neuroblastoma is a malignancy commonly diagnosed during infancy or early childhood, raising speculation about the role of perinatal factors and risk of disease. Using a case-control design, cases included 155 infants and children aged 0-5 years with histologically confirmed neuroblastoma diagnosed and reported to the New York State Cancer Registry between 1976 and 1987. Controls were randomly selected from the State's Livebirth Registry and were frequency matched to cases on year of birth (n = 310). Medical records of cases were used to verify histology and stage of disease. Data on perinatal factors were ascertained from birth certificates and standardised telephone interviews with mothers. Unconditional logistic regression was used to estimate (un)adjusted odds ratios (OR) and 95% confidence intervals (CI). Both preterm (< 37 weeks) and post-term (> 42 weeks) birth were associated with a reduction in risk (OR = 0.4 [CI = 0.1, 0.9] and OR = 0.3 [CI = 0.1, 0.7] respectively) after controlling for confounders in unconditional logistic regression analysis. Elevated risk factors included: smoking during pregnancy (OR = 1.6; CI = 0.9, 2.8), contracted pelvis (OR = 2.3; CI = 0.6, 9.8), birth injury (OR = 2.9; CI = 0.3, 24.9) and 1-min Apgar Score < or =3 (OR = 6.0; CI = 0.9, 38.6); all confidence intervals included one. These data suggest that extremes in gestation may be associated with a reduced risk, although aetiological mechanisms remain unknown.

Patterns of acute leukaemia occurrence among children in the Chernobyl region.

BACKGROUND: The Chernobyl nuclear accident of 1986 released large quantities of radioactive material causing widespread contamination. In the Ukraine alone, more than 4 million people were exposed to radiation. The exact health consequences of this exposure are still being assessed. METHODS: To ascertain the effect of in utero radiation exposure and the development of leukaemia, a review was undertaken of leukaemia sub-types occurring among children born in the year of the accident (1986) and followed 10 years post-exposure. A comparison was made of leukaemia cumulative incidence rates among children from both an exposed and unexposed oblast. RESULTS: Rate ratios (RR) for the all cell types grouping of leukaemia revealed that rates in the exposed Oblast were significantly elevated for females, males and both genders combined. Rates of acute lymphoblastic leukaemia (ALL) were dramatically elevated for males and to a lesser extent for females. For both genders combined, the RR for ALL was more than three times greater in the exposed compared to the unexposed region. CONCLUSION: Study results suggest that the increased risk of leukaemia and acute leukaemia among those children born in 1986 and resident in radioactively contaminated territories may be associated with exposure to radiation resulting from the Chernobyl accident.

Breast cancer risk factors and HER2 over-expression in tumors.

Few epidemiologic studies have investigated the potential role of HER2 in the etiology of breast cancer. We conducted a case-case study of 156 women with incident, invasive ductal carcinoma. Multivariate unconditional logistic regression was used to estimate the odds ratios for a HER2 positive tumor in relation to known and putative risk factors of breast cancer. HER2 status was detected by immunohistochemistry on archival tissue. HER2 positive breast cancers tended to be larger and were less likely to express estrogen receptors, and the incidence rate was higher in patients less than 40 years old. We observed an association between a self-reported history of benign breast disease and the occurrence of HER2 positive breast cancer (OR, 2.1;95% CI, 1.1-4.1). We did not detect associations between HER2 over-expression and family history of breast cancer, parity, late age at first birth, ever having breast fed an infant, or oral contraceptive use. Our findings merit consideration in light of recent evidence of HER2 amplification or over-expression in benign breast disease. Should the link to breast cancer be established, HER2 positive benign breast disease could potentially serve as an early marker for preventive intervention.

The impact of age and sex on the incidence of glial tumors in New York state from 1976 to 1995.

OBJECT: In this study the authors describe secular trends in the incidence of three glial tumors--glioblastoma multiforme (GBM), astrocytoma not otherwise specified (ANOS), and anaplastic astrocytoma (AA)--in New York state from 1976 through 1995. They also describe the effect of age and sex on the relative risk (RR) for these tumors, specifically GBM. METHODS: Crude, age-, and sex-specific incidence rates were calculated for each tumor type from 1976 to 1995 by using data from the New York State Cancer Registry. Age-adjusted incidence rates were calculated by the direct standardization procedure, in which the 1970 United States Census Population Standard Million is used. The RR of GBM for the female population was calculated and plotted. Statistical comparisons were made using Pearson's correlation coefficient and regression analysis with the coefficient of variation. CONCLUSIONS: The age-adjusted incidence of these three glial tumors increased during the study period. Increases in age-specific incidence of GBM were primarily limited to patients 60 years of age or older. The reasons for these increases cannot be fully explained with the data. Those in the female population had a lower risk of developing these tumors than those in the male. For GBM, the protective effect of sex was first evident at the approximate age of menarche, was greatest at the approximate age of menopause, and decreased in postmenopausal age strata. The overall protective effect of female sex and the described trend in RR for GBM in the female population suggests that sex hormones and/or genetic differences between males and females may play a role in the pathogenesis of this tumor.

Parental occupational exposures and risk of neuroblastoma: a case-control study (United States).

BACKGROUND: A case-control study was conducted with 183 histologically confirmed neuroblastoma cases aged 0-14 years diagnosed among residents of New York State, excluding New York City, between 1976 and 1987. Three hundred seventy-two controls were selected from the New York State live birth certificate registry and were matched to cases on year of birth. METHODS: Parental occupational exposures at the time of each child's birth were obtained from maternal telephone interviews, successfully completed for 85% of cases and 87% of controls. RESULTS: Odds ratios were significantly elevated for maternal occupation in the service (OR = 2.0, 95% CI = 1.0 4.1) and retail (OR = 2.0, 95% CI = 1.1-3.7) industries and paternal occupation in materials handling (OR = 3.8, 95% CI = 1.1-14.6). Odds ratios were also significantly elevated for maternal report of occupational exposure to acetone (OR = 3.1, 95% CI = 1.7-5.6), insecticides (OR = 2.3, 95% CI = 1.4-3.7), lead (OR = 4.7, 95% CI = 1.3-18.2) and petroleum (OR = 3.0, 95% CI = 1.5-6.1) and paternal exposure to creosote (OR = 2.1, 95% CI = 1.1-4.3), dioxin (OR = 6.9, 95% CI = 1.3-68.4), lead (OR = 2.4, 95% CI = 1.2-4.8), and petroleum (OR = 1.8, 95% CI = 1.1-2.8). CONCLUSIONS: Due to the uncertainty of the biologic plausibility of these associations and the possibility of alternative explanations, these results should be interpreted cautiously.

Hypothyroidism and diabetes mellitus in an American Indian population.

BACKGROUND: The clinical relationship between diabetes and hypothyroidism is becoming more widely recognized. Although American Indians are disproportionately afflicted with diabetes, the occurrence of hypothyroidism within this group has not been previously reported. METHODS: We present data from a retrospective chart review of health clinic data from a rural isolated northeastern tribe. A total of 156 cases of diabetes and 25 cases of hypothyroidism were identified among 892 eligible individuals living in the service area. RESULTS: Both conditions exhibited strong sex differences. The prevalences of diabetes (21%) and hypothyroidism (5%) among women were higher than those observed among men (13% and 0.2%, respectively). The overall prevalence of hypothyroidism among women with diabetes (8.8%) varied by age ranging from 5% among women younger than 60 years to 21% among women aged 60 years and older. CONCLUSIONS: Our findings support the need for further investigation of the association between diabetes and hypothyroidism in American Indian populations with high prevalence rates of diabetes. This association may be of particular interest to family physicians and other clinicians caring for American Indian populations.

[Use of etoposide, ifosfamide and cisplatin (EIP) for treatment of inoperable non-small cell lung cancer]. / Zastosowanie Etopozydu, ifosfamidu i Cysplatyny (EIP) w leczeniu nieoperacyjnych postaci niedrobnokomórkowego raka pluca.

Recent studies have pointed out that chemotherapy can prolong life in advanced inoperable cancer patients. A clinical study to evaluate response and toxicity of the combination of etoposide, ifosfamide and cisplatin (EIP) in the treatment of inoperable non-small cell lung cancer was performed. 25 patients entered the study. Treatment consisted of etoposide 120 mg/m2 given i.v. on days 1-3, ifosfamide 1.5 g/m2 given i.v. on days 1-5 with mesna protection and cisplatin 20 mg/m2 given i.v. on days 1-5. Cycles were repeated every 4 weeks for a maximum of 6 in responders. 16 (64%) patients responded to treatment, 13 (52%) reached partial and 3 (12%) complete remission. In two recurrent cases second remission was achieved after reinstitution of the EIP regimen. Median survival time was 13 months (range 7-48 months) for responders and 5 months (range 2-11 months) for non-responders. Overall treatment was well tolerated with granulocytopenia being the most frequent toxicity. The results are encouraging for further investigations. Application of higher doses of ifosfamide with colony stimulating factors protection is planned.

Expression of p27(Kip1) and bcl-2, cigarette smoking, and colorectal cancer risk.

Although a positive association between cigarette smoking and colorectal adenoma development is consistently found, the association with colorectal cancer remains controversial. We evaluated the potential roles of p27(Kip1) and bcl-2 protein expressions in conjunction with cigarette smoking exposure and colorectal cancer risk in a hospital-based case-control study. A total of 163 colorectal cancer patients from Roswell Park Cancer Institute and Buffalo General Hospital and 326 healthy controls responded to a standardized questionnaire on colorectal cancer risk factors including detailed information on their history of cigarette smoking; 110 of the patients' tumours were available for immunohistochemical analysis of p27(Kip1) and bcl-2 protein overexpression. An avidin-biotin immunoperoxidase procedure was used to determine expression after incubation with mouse monoclonal p27(Kip1) and mouse monoclonal bcl-2 antibodies, respectively. A statistically significant trend for total pack-years of smoking was found when p27(Kip1) positive cases were compared with p27(Kip1) negative cases (trend test, p = 0.007). Although a weak inverse association was observed with smoking exposure among p27(Kip1) negative tumour cases in comparison to controls, a significant dose-response association was seen with p27(Kip1) positive tumours. The relative risk of developing a p27(Kip1) positive tumour was estimated to be 1.17 (95% CI 0.54-2.54) for those with less than 20 pack-years, 1.95 (95 % CI 0.95-3.97) for those with 20-39 pack-years, and 2.25 (95% CI 1.14-4.45) for those with greater than 39 pack-years of smoking exposure (trend test, p = 0.009) when compared with controls. When cases with bcl-2 expression were compared with cases without bcl-2 expression, suggestion of a trend was also observed with pack-years smoked (trend test, p = 0.09). In our study of 110 patients with sporadic colorectal cancer and 326 controls, we observed differences in associations between cigarette smoking and expressions in p27(Kip1) and bcl-2. Our data suggest that bcl-2 overexpression (or a bcl-2 dependent pathway) is associated with cigarette smoking in the development of colorectal cancer, whereas a loss of p27(Kip1) expression is not. These associations indicate that there is aetiological heterogeneity in colorectal cancer development, and that they can indirectly allude to where these changes in protein expression occur in the adenoma-carcinoma sequence (i.e. early versus late events).

Risk of premenopausal breast cancer in association with occupational exposure to polycyclic aromatic hydrocarbons and benzene.

OBJECTIVES: This study examined the relationship between risk of premenopausal breast cancer and occupational exposure to benzene and polycyclic aromatic hydrocarbons (PAH) and whether the proposed relationship between PAH and breast cancer differed by tumor estrogen receptor (ER) status. METHODS: In a case-referent study of premenopausal breast cancer, occupational histories and other information were obtained through interviews, and job-exposure matrices were used to assess exposure to PAH and benzene. RESULTS: A dose-response relationship for the probability of exposure to benzene [low: odds ratio (OR) 1.64, 95% confidence interval (95% CI) 0.64-4.21; high: OR 1.95, 95% CI 1.14-3.33) and to PAH (low: OR 1.56, 95% CI 0.78-3.12; high: OR 2.40, 95% CI 0.96-6.01). Risk increased with duration of exposure to benzene, but not to PAH. A dose-response relationship was not evident for the intensity of exposure to benzene or to PAH. When analyses were stratified by tumor ER status, PAH exposure was related to a greater increase in the risk of ER-positive (OR 2.27, 95% CI 1.14-4.54) than ER-negative (OR 1.12, 95% CI 0.47-2.64) breast cancer. Risk of ER-positive, but not ER-negative, tumors increased with the probability of exposure to PAH. CONCLUSIONS: The findings suggest an association between risk and occupational exposure to benzene. Although it was difficult to study PAH independently of benzene, there was some suggestion of an association between PAH exposure and ER-positive tumors. These data should be interpreted with caution because of the limitations of this study, including low-response rates and small numbers of exposed persons.

The health status of American Indians and Alaska Natives: 2. Lessons for cancer educators.

Malignant disease is largely unrecognized as a leading cause of death among American Indians and Alaska Natives (AI/ANs). Published studies of cancer incidence, cancer mortality, and cancer survival are highlighted to present an overview on the epidemiology of cancer among Native peoples. Cancer incidence and mortality have demonstrated steady increases among AI/ANs during a relatively limited time frame, as well as unique patterns of site-specific cancers. Cancer-survival data reveal that Native peoples have the poorest survival of any racial group for all cancer sites combined and for eight of the ten leading sites. Opportunities to educate health care providers, through continuing medical education programs and focused conferences for postdoctoral and current medical trainees, can be used to enhance cultural sensitivity and to examine ethnic differences in cancer patterns. Enhancement of recognition of the unique cancer patterns among AI/AN populations may lead to improved identification of at-risk individuals and more effective cancer screening programs within Native communities.

Risk of premenopausal breast cancer and patterns of established breast cancer risk factors among teachers and nurses.

BACKGROUND: Contrasting results have been published regarding the risk of breast cancer among teachers and nurses. Confounding by reproductive factors may explain the increased risk observed among women in these occupations as information on those factors were not available in most studies. METHODS: We examined the risk of premenopausal breast cancer among teachers and nurses using occupational histories in a case-control study where information on established risk factors was available. RESULTS: Having ever held a teaching job was not related to breast cancer (OR = 0.74, 95% CI = 0.44-1.28) and women who worked for 10 years or less in this occupation had a non-significant deficit of risk (OR = 0.52, 95% CI = 0.27-1.02). No elevation in risk was found in association with having ever been a nurse (OR = 0.85, 95% CI = 0.45-1.61) or with duration of nursing. Although direct comparison of established risk factors among teachers and nurses and other women in the study showed some evidence of differential distribution, especially when comparing teachers to other women, adjustment for reproductive variables and other breast cancer risk factors did not change the results of this study. CONCLUSION: These findings suggest that teachers and nurses are not at an increased risk of breast cancer. This study also suggests that established risk factors for premenopausal breast cancer may not explain the elevation of risk found in other studies of teachers and nurses. However, this conclusion is limited by the fact that in the present study teachers and nurses had lower than expected breast cancer risk with or without adjustment for established risk factors. Limitations of this study such as low response rates and limited statistical power should be considered in the interpretation of these findings.