Arm lymphoedema after axillary surgery in women with invasive breast cancer.

BACKGROUND: The primary aim was to compare arm lymphoedema after sentinel lymph node biopsy (SLNB) alone versus axillary lymph node dissection (ALND) in women with node-negative and node-positive breast cancer. The secondary aim was to examine the potential association between self-reported and objectively measured arm lymphoedema. METHODS: Women who had surgery during 1999-2004 for invasive breast cancer in four centres in Sweden were included. The study groups were defined by the axillary procedure performed and the presence of axillary metastases: SLNB alone, ALND without axillary metastases, and ALND with axillary metastases. Before surgery, and 1, 2 and 3 years after operation, arm volume was measured and a questionnaire regarding symptoms of arm lymphoedema was completed. A mixed model was used to determine the adjusted mean difference in arm volume between the study groups, and generalized estimating equations were employed to determine differences in self-reported arm lymphoedema. RESULTS: One hundred and forty women had SLNB alone, 125 had node-negative ALND and 155 node-positive ALND. Women who underwent SLNB had no increase in postoperative arm volume over time, whereas both ALND groups showed a significant increase. The risk of self-reported arm lymphoedema 1, 2 and 3 years after surgery was significantly lower in the SLNB group compared with that in both ALND groups. Three years after surgery there was a significant association between increased arm volume and self-reported symptoms of arm lymphoedema. CONCLUSION: SLNB is associated with a minimal risk of increased arm volume and few symptoms of arm lymphoedema, significantly less than after ALND, regardless of lymph node status.

A prospective, multicenter validation study of a prognostic index composed of S-phase fraction, progesterone receptor status, and tumour size predicts survival in node-negative breast cancer patients: NNBC, the node-negative breast cancer trial.

BACKGROUND: In a retrospective study on node-negative breast cancer, a prognostic index consisting of a proliferation factor, S-phase fraction (SPF), progesterone receptor status (PR), and tumour size identified one-third of patients as high risk, with a sixfold increased risk of breast cancer death. This prospective multicenter cohort study was set up to validate the index. PATIENTS AND METHODS: In 576 T1-2N0 patients <60 years, prospective analyses of PR and SPF were carried out. High risk was defined as ≥2 of the following: size >20 mm, PR-negativity, and high SPF (in the absence of SPF, Bloom-Richardson grade 3). Median follow-up was 17.8 years. RESULTS: Thirty-one percent were high risk. In univariate analysis, the index was prognostic for breast cancer-specific survival after 5 years [hazard ratio (HR) = 4.7, 95% confidence interval (95% CI) 2.5-8.9], 10 years (HR = 2.2, 95% CI 1.5-3.3), and 15 years (HR = 1.7, 95% CI 1.2-2.5), and remained significant after adjustment for adjuvant medical treatment and age. In the 37% of patients with no risk factors, only one patient died of breast cancer the first 5 years. CONCLUSIONS: This prospective study validates a prognostic index consisting of a proliferation factor, PR-status, and tumour size. The index may be helpful for prognostic considerations and for selection of patients in need of adjuvant therapy.

Axillary recurrence rate 5 years after negative sentinel node biopsy for breast cancer.

BACKGROUND: Sentinel lymph node (SLN) biopsy has replaced axillary lymph node dissection (ALND) as the standard axillary staging procedure in breast cancer. Follow-up studies in SLN-negative women treated without ALND report low rates of axillary recurrence, but most studies have short follow-up, and few are multicentre studies. METHODS: Between September 2000 and January 2004, patients who were SLN-negative and did not have ALND were included in a prospective cohort. Kaplan-Meier estimates were used to analyse the rates of axillary recurrence and survival. The risk of axillary recurrence was also compared in centres with high and low experience with the SLN biopsy (SLNB) technique. RESULTS: A total of 2195 patients with 2216 breast tumours were followed for a median of 65 months. Isolated axillary recurrence was diagnosed in 1·0 per cent of patients. The event-free 5-year survival rate was 88·8 per cent and the overall 5-year survival rate 93·1 per cent. There was no difference in recurrence rates between centres contributing fewer than 150 SLNB procedures to the cohort and centres contributing 150 or more procedures. CONCLUSION: This study confirmed the low risk of axillary recurrence 5 years after SLNB for breast cancer without ALND.

Acute colonic diverticulitis: a systematic review of diagnostic accuracy.

OBJECTIVE: To appraise the literature on the diagnosis of acute colonic diverticulitis by ultrasound (US), computed tomography (CT), barium enema (BE) and magnetic resonance imaging (MRI). METHOD: The databases of Pub Med, the Cochrane Library and EMBASE were searched for articles on the diagnosis of diverticulitis published up to November 2005. Studies where US, CT, BE, or MRI were compared with a reference standard on consecutive or randomly selected patients were included. Three examiners independently read the articles according to a prespecified protocol. In case of disagreement consensus was sought. The level of evidence of each article was classified according to the criteria of the Centre for Evidence-Based Medicine (CEBM), Oxford, UK. RESULTS: Forty-nine articles relevant to the subject were found and read in full. Twenty-nine of these were excluded. Among the remaining 20 articles, only one study, evaluating both US and CT reached level of evidence 1b according to the CEBM criteria. Two US studies and one MRI study reached level 2b. The remaining studies were level 4. CONCLUSION: The best evidence for diagnosis of diverticulitis in the literature is on US. Only one small study of good quality was found for CT and for MRI-colonoscopy.

A randomised study of axillary drainage and pectoral fascia preservation after mastectomy for breast cancer.

BACKGROUND: To reduce the risk of seroma after modified radical mastectomy in breast cancer patients, the use of suction axillary drainage is a standard procedure. The optimal time to remove the drain is not established. Whether the removal or preservation of the pectoral fascia influences the risk of seroma formation or loco-regional recurrence rate remains unclear. METHOD: The trial included 247 patients with breast cancer who underwent modified radical mastectomy in five Swedish hospitals 1993-1997. The median follow-up time was 6 years. One hundred and twenty-two and 125 patients, respectively, were randomised between removal versus preservation of the pectoral fascia. Of these 247 patients a total of 198 patients were also randomised to have the drain removed 24 h postoperatively or to keep the drain in until discharge had decreased to less than 40 ml/24 h. RESULTS: Early removal of the axillary drain was associated with significantly more seromas and a shorter average postoperative hospital stay. There were no differences between the two groups regarding the rate of wound infections and/or hematoma formation. Removal or preservation of the pectoral fascia did not influence the formation of seroma or the amount of peroperative bleeding. A trend towards an increased risk for chest wall recurrence was observed in patients with preserved pectoral fascia (16/125 compared with 8/122; hazard ratio=2.0, 95% confidence interval=0.9-4.7). CONCLUSION: Early removal of axillary drain shortened the duration of hospital stay without any increase in wound complications. However, it yielded a significantly higher incidence of seroma. Seroma formation and the chest wall recurrence rate was not significantly influenced by the preservation of the pectoral fascia or not.

Risk factors for local recurrence after breast-conserving surgery.

BACKGROUND: It is not clear whether risk factors for local recurrence after breast-conserving surgery differ in women having surgery for in situ or invasive cancer. Furthermore, the Nottingham Prognostic Index (NPI) and Nottingham Histological Grade (NHG) have been little studied as determinants of local recurrence risk. METHOD: In a case-control study (491 cases and 1098 controls) nested within a cohort of 7502 women who had surgery for in situ or invasive cancer of the breast, patient characteristics, tumour characteristics and treatment-related variables were evaluated as risk factors for local recurrence. RESULTS: Multivariate conditional logistic regression analyses showed that age below 40 years, tumour multicentricity and an unclear or unknown surgical margin were significant risk factors for local recurrence. Radiotherapy to the breast and adjuvant hormone therapy were protective. Cancer in situ was not associated with a higher risk of local recurrence than invasive cancer (odds ratio 1.0, 95 per cent confidence interval 0.8 to 1.3). NHG and NPI were not helpful in determining risk of local recurrence. CONCLUSION: Margin status, age, tumour multicentricity, and use of radiotherapy and adjuvant hormone therapy were important determinants of risk of local recurrence. With the exception of surgical margin, variables related to the quality of surgical management did not predict risk of local recurrence.

Dexamethasone is as effective as ondansetron for the prevention of postoperative nausea and vomiting following breast surgery.

INTRODUCTION: Postoperative nausea and vomiting remain a common problem following breast surgery. This study assesses whether dexamethasone is as effective as ondansetron in the control of postoperative nausea and vomiting (PONV). METHODS: Eighty ASA I-III patients undergoing breast surgery for carcinoma of the breast were included in the study. Following premedication with diazepam 5-10 mg, patients were induced with fentanyl 50 micro g and propofol 2-2.5 mg kg-1. A larynx mask was inserted and anesthesia maintained with sevoflurane in oxygen and nitrous oxide. Patients were then randomly divided into two groups: Group D (dexamethasone) was given 4 mg dexamethasone i.v. after induction and Group O (ondansetron) was given 4 mg ondansetron at the same time point. Postoperatively, nausea, vomiting and pain were recorded at 1-h intervals during 4 h, and thereafter every 4 h during 24 h. RESULTS: The incidence of PONV during 24 h was 37% and 33% in Group D and Group O, respectively (NS). No differences were found between the groups in the incidence of postoperative nausea, vomiting or pain at the different time intervals. No differences were found in the incidence of PONV in smokers vs. non-smokers. No side-effects of these drugs were observed. CONCLUSIONS: Ondansetron 4 mg or dexamethasone 4 mg are equally effective in the prevention of postoperative nausea and vomiting following breast surgery. Other factors being similar, the difference in cost between these drugs would favor the use of dexamethasone instead of ondansetron when monotherapy against PONV is used.

Is postoperative radiotherapy after breast conserving surgery always mandatory? A review of randomised controlled trials.

BACKGROUND AND AIMS: Breast-conserving surgery followed by radiotherapy, in order to prevent local recurrence, has been the treatment of choice ever since breast conserving surgery was introduced in clinical practice. Patient selection, type of surgery, dose and type of radiotherapy, however, may have an impact on the risk of local recurrence. The aim of this review is to synthesise the results from randomised trials and try and define a subgroup of patients in whom postoperative radiotherapy could be omitted. METHOD: A literature search of Pub Med and The Cochrane randomised trials registry identified six trials comparing patients randomised to surgery alone or surgery plus radiotherapy, two trials comparing different radiotherapy modalities and one trial comparing different types of surgery. RESULTS: Addition of postoperative radiotherapy reduce the risk of local recurrence by 2/3. The dose-intensity of radiotherapy and surgery has a positive impact on local control. Patients at low risk of local recurrence are patients > 55 years of age, with stage I tumours and favourable histology treated with adequate resection margins. No trial showed any positive effect of radiotherapy on survival. CONCLUSION: In most patients postoperative radiotherapy is an integral part of breast-conservation. Radiotherapy can be omitted in selected low risk patients.

Local recurrence in the breast after conservative surgery--a study of prognosis and prognostic factors in 391 women.

In a population-based cohort of 6613 women with invasive breast cancer, who had breast-conserving surgery between 1981 and 1990, 391 recurrences in the operated breast were identified. The main aim of this study was to examine the prognosis and prognostic factors in different subgroups of local recurrences, characterised by the time to recurrence, location of recurrence and previously given radiotherapy. The median follow-up for women who had a local recurrence was 7.9 years. The life-table estimates for breast cancer-specific survival in women with local recurrences were 84.5% (standard error (S.E.) 1.8) at 5 years and 70.9% (S.E. 2.7) at 10 years. The risk of breast cancer death was highest among women who had an early (

Consequences of axillary recurrence after conservative breast surgery.

BACKGROUND: The aim was to study the incidence, time course and prognosis of patients who developed axillary recurrence after breast-conserving surgery, and to evaluate possible risk factors for axillary recurrence and prognostic factors after axillary recurrence. METHODS: In a population-based cohort of 6613 women with invasive breast cancer who had breast-conserving surgery between 1981 and 1990, 92 recurrences in the ipsilateral axilla were identified. Risk factors for axillary recurrence were studied in a case-control study nested in the cohort, and late survival was documented in the women with axillary recurrence. RESULTS: The overall risk of axillary recurrence was 1.0 per cent at 5 years and 1.7 per cent at 10 years. The risk of axillary recurrence increased with tumour size (P = 0.033) and was highest in younger women (odds ratio (OR) 3.9 for women aged less than 40 years compared with those aged 50-59 years). Radiotherapy to the breast reduced the risk of axillary recurrence (OR 0.1 (95 per cent confidence interval 0.1 to 0.4)). The breast cancer-specific survival rate after axillary recurrence, as measured from primary treatment, was 78.0 per cent at 5 years and 52.3 per cent at 10 years. Tumour size and node status had a statistically significant effect on death from breast cancer. CONCLUSION: Axillary recurrence is rare, although more common in younger women with large tumours. Radiotherapy to the breast was protective. Tumour size and node status were the most important prognostic factors in women with axillary recurrence.

Five-node biopsy of the axilla: an alternative to axillary dissection of levels I-II in operable breast cancer.

BACKGROUND: Axillary clearance of patients with early breast cancer is accompanied by a high risk of arm morbidity. Less invasive ways to establish the axillary nodal status are therefore of interest, especially in women with low risk of nodal metastases. METHODS: Four hundred and fifteen breast cancer patients (clinical stage T(0-3) N(0-1) M(0)) were operated in the axilla with a five-node biopsy followed in the same operation by a further dissection of levels I-II of the axilla in order to evaluate the accuracy of the five-node node biopsy compared with level I-II dissection. RESULTS: In all patients the sensitivity of the five-node biopsy was 97.3% with a negative predictive value of 98.5% and a negative likelihood ratio of 0.027. Among cases detected by screening (n=204) and those clinically detected (n=197) the sensitivity of the five-node biopsy was 95.8% and 97.9% respectively, with negative predictive values of 98.7% and 98.0% and negative likelihood ratios of 0.042 and 0.021 respectively. CONCLUSION: Five-node biopsy of the axilla has good accuracy for correctly staging the axilla in both clinically and screening-detected cases. Five-node biopsy is an alternative to axillary clearance and sentinel node biopsy in patients with operable breast cancer.

Multicentre study of detection and false-negative rates in sentinel node biopsy for breast cancer.

BACKGROUND: Sentinel node biopsy has recently evolved as a means of staging the axilla in breast cancer with minimal surgical trauma. The aim of this prospective multicentre study was to identify factors that influenced the detection and false-negative rates during the learning phase. METHODS: Data on all 498 sentinel node biopsies performed between August 1997 and December 1999 in Sweden were collected. RESULTS: A sentinel node was found in 450 patients (90 per cent). Preoperative scintigraphy visualized 83 per cent of all sentinel nodes. The detection rate was higher with same-day injection of tracer than with injection the day before (96 versus 86 per cent; P < 0.01). Dye injected less than 5 min or more than 30 min before the start of the operation lowered the detection rate (less than 60 per cent versus more than 65 per cent; P = 0.02). The detection rate varied from 61 to 100 per cent between surgeons. The false-negative rate was 11 per cent. The presence of multiple tumour foci and a high S-phase fraction increased the risk of a false-negative sentinel node, whereas the number of operations performed by each surgeon was less important. CONCLUSION: Training of the individual surgeon influenced the detection rate, as did timing of tracer and dye injection. The false-negative rate seemed to be related to biological factors.

Case-control study on concentrations of organohalogen compounds and titers of antibodies to Epstein-Barr virus antigens in the etiology of non-Hodgkin lymphoma.

A rapid increase in incidence of non-Hodgkin lymphoma (NHL) has been reported from many countries. Exposure to certain pesticides and organochlorines has been shown to be risk factors. Epstein-Barr virus (EBV) is a human herpesvirus that has been associated with some subgroups of NHL, such as Burkitt lymphoma and lymphomas related to severe immunosuppression. In this study, we measured lipid adjusted blood concentrations of 36 congeners of polychlorinated biphenyls (PCBs), p,p'-dichlorodiphenyl-dichloroethylene (p,p'-DDE), hexachlorobenzene (HCB), four different subgroups of chlordanes (trans-nonachlordane, cis-nonachlordane, MC6 and oxychlordane) and 2,2',4,4'-tetrabrominated diphenyl ether (TBDE) in incident cases of NHL and controls from the general population. Titers of antibodies to the Epstein-Barr early antigen (EA) were correlated to concentrations of organochlorines. We found a significant difference in lipid adjusted blood concentrations of total PCBs and TBDE between cases and controls. Titers of antibodies to EA IgG > 80 were correlated to an increased risk for NHL with odds ratio (OR) = 1.9, 95% confidence interval (CI) =0.94-3.8. This risk was further increased in those with a level above the median value of "sum of PCBs" (OR=4.0, CI=1.2-14), HCB (OR=5.3, CI=1.6-19), sum of chlordanes (OR=4.0, CI=1.2-14) and TBDE (OR=21, CI=4.6-124), suggesting an interaction between EBV and a higher concentration of these chemicals. Also for the "sum of immunotoxic PCBs" increased risk was found in that group (OR=6.4, CI=1.9-24). Subdivision of NHL in histological types yielded highest risks for low-grade B-cell NHL.

Adipose tissue concentrations of dioxins and dibenzofurans, titers of antibodies to Epstein-Barr virus early antigen and the risk for non-Hodgkin lymphoma.

A rapid increase in the incidence of non-Hodgkin lymphoma (NHL) has been reported in many countries. Exposure to certain pesticides or organochlorines has been shown to be a risk factor. Epstein-Barr virus (EBV) is a human herpesvirus that has been associated with some subgroups of NHL, such as Burkitt lymphoma and lymphomas related to severe immunosuppression. In this study we measured concentrations of dioxins and dibenzofurans in 33 NHL cases and 39 surgical controls. For 23 of the cases and 32 of the controls EBV titers were also available. Median titer of antibodies to EBV early antigen (EA) IgG was higher in patients than in controls. Concentrations of dioxins and dibenzofurans were divided into two groups according to the median concentration for the controls. Unconditional logistic regression analysis was performed adjusting for sex, age, and body mass index. For several higher chlorinated congeners increased risk was found for patients in the high-concentration and high-titer group. For toxic equivalency factor >27.79 and EA>80 an odds ratio of 2.8 with 95% confidence interval 0.52-18 was calculated. These results indicated that current exposure to certain organochlorines in combination with EBV might increase the risk for NHL.

Pressurized-fluid extraction (PFE) of chlorinated paraffins from the biodegradable fraction of source-separated household waste.

A method is presented in which pressurized-fluid extraction (PFE) is used for the extraction of chlorinated paraffins (CP) from the biodegradable fraction of source-separated household waste. The conditions that were optimized for high recovery in the extraction procedure were extraction time, temperature, and the use of different solvents and different sample particle sizes, Recoveries of CP from fortified household waste material were over 90%, with only few interferences when cyclohexane was used as solvent. Extraction yields from contaminated samples containing CP were further compared with recoveries obtained by use of Soxtec extraction. The results showed that PFE is a rapid, low-solvent-consuming technique, giving high yields.

Time trends in the results of breast conservation in 4694 women.

In a population-based cohort of 4694 women with invasive breast cancer, operated upon with breast conserving surgery (BCS) in 1981--1990 and followed through to 1997, we studied how this technique had been adopted into clinical practice, especially with reference to the use of radiotherapy (RT). Our main aim was to see whether there was a drift in the risk of local recurrence and breast cancer death over time. During the 30,151 person-years of observation in the cohort, there were 582 local recurrences, 456 breast cancer deaths and 438 deaths due to other causes. Postoperative RT was given to 70.2%, but usage increased over the period. The women not receiving RT were mostly elderly, but also in women <70 years, 20.4% did not receive RT. The risk for local recurrence after RT were 7.6 and 17.8% at 5 and 10 years, respectively. Without RT, more than 30% had a local recurrence at 10 years. Thus, the choice not to irradiate failed to target women at a low risk. In a multivariate Cox analysis taking tumour size, nodal status, age at operation and RT into account, there was a trend for a higher risk of local recurrence in the later time period, relative hazard 1.5 (95% confidence interval (CI) 1.0--2.1). Corrected survival was 93.3 and 85.2% at 5 and 10 years, respectively.

Sentinel node in breast cancer--a Swedish pilot study of 75 patients.

OBJECTIVE: To find out if the sentinel node can be detected in sufficient numbers of women with breast cancer to be useful as a prognostic sign, whether it reflects that state of the entire axilla, and whether it detects micrometastases that would otherwise be missed. DESIGN: Prospective study. SETTING: 3 teaching hospitals, Sweden. SUBJECTS: 75 patients with breast cancer who were listed to have axillary dissection as well as resection of their tumour. INTERVENTIONS: Injection of 99Tc nanocolloid 0.4 ml and patent blue dye 1 ml around the tumour or under the skin above the tumour, followed by preoperative lymphoscintigraphy and then identification of the sentinel node during operation either because it had turned blue or with a gamma probe. Removal of the sentinel node and complete axillary dissection. MAIN OUTCOME MEASURES: Identification of the sentinel node and presence of metastatic nodes in the axilla. RESULTS: The sentinel node was identified in 69/75 (92%). It correctly predicted the state of the axilla in 66/69 (96%), and detected metastases in 24 of the 27 with invaded nodes in the axilla (89%). The false negative rate was 11%. In 14/27 with axillary metastases (52%) the sentinel node was the only involved node. In 3/24, metastases were detected by immunohistochemistry alone. CONCLUSION: Biopsy of the sentinel node predicted the presence or absence of axillary metastases with acceptable accuracy. However, before axillary node dissection is rejected in favour of sentinel node biopsy alone, large multicentre studies are needed to establish the true false negative rate.

10-Year results after sector resection with or without postoperative radiotherapy for stage I breast cancer: a randomized trial.

PURPOSE: To study the long-term effectiveness of postoperative radiotherapy after sector resection for breast cancer in a randomized trial in which mammography is a major pathway to diagnosis. PATIENTS AND METHODS: Three hundred eighty-one women with a unifocal breast cancer < or = 20 mm in diameter on the preoperative mammogram and without histopathologic signs of axillary metastases were treated by sector resection plus axillary dissection. Of these patients, 184 women were randomized to receive postoperative radiotherapy to the breast (XRT group), and 197 women received no further treatment (non-XRT group). RESULTS: The local recurrence rate was 8.5% (95% confidence interval [CI], 3.9% to 13.1%) in the XRT group and 24.0% (95% CI, 17.6% to 30.4%) in the non-XRT group (P =.0001). Survival free from regional and distant recurrence was 83. 3% in the XRT group (95% CI, 77.5% to 89.1%) and 80.0% in the non-XRT group (95% CI, 73.9% to 86.1%) (P =.23). Overall survival was 77.5% in the XRT group (95% CI, 70.9% to 84.1%) and 78% in the non-XRT group (95% CI, 71.7% to 84.3%) (P =.99). A subgroup analysis suggested that women older than 55 years of age without comedo or lobular carcinomas had a low risk of local recurrence of 6.1% (95% CI, 0.1% to 9.1%) in the XRT-group and 11.0% (4.0% to 18.0%) in the non-XRT group (P =.16). CONCLUSION: Sector resection plus radiotherapy resulted in an absolute reduction in local recurrence of 16% at 10 years compared with surgery alone. Women older than 55 years of age without comedo or lobular carcinomas may have a low risk of local recurrence. Postoperative radiotherapy was not shown to reduce distant recurrences or improve overall survival.

Case-control study on breast cancer and adipose tissue concentrations of congener specific polychlorinated biphenyls, DDE and hexachlorobenzene.

In a case-control study on 43 patients operated for invasive breast cancer (cases) and 35 patients operated for benign breast disease (controls) adipose tissue concentrations of polychlorinated biphenyls (PCBs), 1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene (DDE) and hexachlorobenzene (HCB) were investigated. Approximately 10 g of breast tissue free from tumour was taken and frozen until analysis. No significant difference for the sum of non co-planar PCBs or DDE was found between cases and controls. For postmenopausal women the odds ratio (OR) was increased for co-planar PCB #77 > 4.5 pg/g lipid (OR = 5.8, 95% confidence interval (CI) = 0.8-42), PCB #126 > 145 pg/g lipid (OR = 2.2, 95% CI = 0.2-18), PCB #169 > 90 pg/g lipid (OR = 7.8, 95% CI = 0.6-96), and for HCB > 40 ng/g lipid (OR = 1.9, 95% CI = 0.4-7.2) adjusted for age and parity. The risk increased further for postmenopausal women with oestrogen receptor positive tumours yielding for PCB #77 adjusted OR 33 (95% CI 1.8-588), PCB #126 OR not calculable (no unexposed cases), PCB #169 OR 8.6 (95% CI 0.5-136) and hexachlorobenzene OR 7.1 (95% CI 1.1-45). Also for the sum of PCB > 1230 ng/g lipid adjusted OR increased to 1.8 (95% CI 0.4-7.3) whereas the results were similar for DDE.

Some aspects of the etiology of non-Hodgkin's lymphoma.

In epidemiologic studies, non-Hodgkin's lymphoma (NHL) has been associated with exposure to chemicals such as phenoxyacetic acids; chlorophenols; dioxins; organic solvents including benzene, polychlorinated biphenyls, chlordanes; and immunosuppressive drugs. Experimental evidence and clinical observations indicate that these chemicals may impair the immune system. The risk is increased for NHL in persons with acquired and congenital immune deficiency as well as autoimmune disorders. Also, certain viruses have been suggested to be of etiologic significance for NHL. In some cases of NHL the common mechanism for all these agents and conditions may be immunosuppression, possibly in combination with viruses.