Lung cancer histology, stage, treatment, and survival in American Indians and Alaska Natives and whites.

BACKGROUND: Studies of lung cancer disparities between American Indians and Alaska Natives (AIANs) and whites have yielded mixed results. To the authors' knowledge, no studies to date have investigated whether race-based differences in histology could explain survival disparities. METHODS: Data were obtained on AIANs and whites with lung cancer from the 17 population-based cancer registries participating in the Surveillance, Epidemiology, and End Results (SEER) program from 1973 to 2006. Logistic regression was used to determine whether race and other covariates were associated with histology, stage at diagnosis, and receipt of surgery. Cox regression was used to determine the risk of death associated with race, after adjusting for histology, stage, and other covariates. RESULTS: Histology, but not race, was found to be associated with stage at diagnosis, and both race and stage were found to be associated with histology. AIANs were less likely to receive surgery than whites, after adjusting for patient and tumor characteristics. Survival improved for both AIANs and whites after 2000, compared with the 1973 through 1999 period, but survival was consistently shorter for AIANs. The association between AIAN race and decreased survival was strongest in the later time period. CONCLUSIONS: Lung cancer histology appears to be associated with tumor characteristics, treatment, and survival. AIAN race is associated with tumor histology, receipt of surgery, and survival. In the future, studies with access to smoking data, patient comorbidity information, and health systems-level data will be able to identify factors responsible for the disparities observed in these analyses.

Effect of radiotherapy interruptions on survival in medicare enrollees with local and regional head-and-neck cancer.

PURPOSE: To investigate whether interruptions in radiotherapy are associated with decreased survival in a population-based sample of head-and-neck cancer patients. METHODS AND MATERIALS: Using the Surveillance, Epidemiology, and End Results-Medicare linked database we identified Medicare beneficiaries aged 66 years and older diagnosed with local-regional head-and-neck cancer during the period 1997-2003. We examined claims records of 3864 patients completing radiotherapy for the presence of one or more 5-30-day interruption(s) in therapy. We then performed Cox regression analyses to estimate the association between therapy interruptions and survival. RESULTS: Patients with laryngeal tumors who experienced an interruption in radiotherapy had a 68% (95% confidence interval, 41-200%) increased risk of death, compared with patients with no interruptions. Patients with nasal cavity, nasopharynx, oral, salivary gland, and sinus tumors had similar associations between interruptions and increased risk of death, but these did not reach statistical significance because of small sample sizes. CONCLUSIONS: Treatment interruptions seem to influence survival time among patients with laryngeal tumors completing a full course of radiotherapy. At all head-and-neck sites, the association between interruptions and survival is sensitive to confounding by stage and other treatments. Further research is needed to develop methods to identify patients most susceptible to interruption-induced mortality.

Completion of radiotherapy for local and regional head and neck cancer in medicare.

OBJECTIVE: To identify factors associated with interruption or early discontinuation of treatment in patients receiving radiotherapy for head and neck cancer, because it is believed that such treatment interruption or early discontinuation increases the risk of disease relapse and adversely influences survival. DESIGN, SETTING, AND PATIENTS: Using the Surveillance, Epidemiology, and End Results (SEER)-Medicare linked database, we identified Medicare beneficiaries 66 years or older who were diagnosed as having local or regional head and neck cancer from January 1, 1997, through December 31, 2003. For each case, we calculated the timing and duration of radiotherapy using Medicare claims data. We then performed logistic regression analyses to estimate the association between tumor and clinical characteristics and early discontinuation of and/or interruptions in radiotherapy. MAIN OUTCOME MEASURE: Completion of uninterrupted radiotherapy. RESULTS: A substantial proportion of patients (39.8% overall) had interruptions in radiotherapy and/or incomplete therapy. Altogether, 70.4% of surgical patients completed radiotherapy with no interruptions compared with 52.0% of nonsurgical patients (chi(2) = 78.17; P < .001). Surgery was associated with an increased likelihood of completing uninterrupted radiotherapy for all tumor sites. Comorbidity, chemotherapy, and regional disease were all associated with a decreased likelihood of completing radiotherapy at a subset of sites. CONCLUSIONS: Failure to complete uninterrupted radiotherapy is common among Medicare enrollees with head and neck cancer. Surgery before radiotherapy is associated with an increased likelihood of completing radiotherapy. At a subset of sites, chemotherapy is associated with a decreased likelihood of completing radiotherapy. Further research is needed to identify factors associated with noncompletion of radiotherapy among nonsurgical patients and patients who receive chemotherapy.

Association between the peroxisome proliferator-activated receptor gamma Pro12Ala variant and haplotype and pancreatic cancer in a high-risk cohort of smokers: a pilot study.

OBJECTIVES: The Pro12Ala variant in the peroxisome proliferator-activated receptor gamma (PPARG) gene has been associated with diabetes and several cancers. This pilot study tested for the association between Pro12Ala and pancreatic cancer risk in a high-risk sample of smokers. METHODS: A nested case-control study was conducted in 83 incident cases of pancreatic cancer and 166 matched controls originally recruited into a cohort chemoprevention study of lung cancer. Associations between Pro12Ala and pancreatic cancer risk were measured using conditional logistic regression. RESULTS: Carriers of the G allele (Ala) of the Pro12Ala variant had a borderline increased relative risk of pancreatic cancer compared with homozygous carriers of the C allele (Pro), with an odds ratio of 1.79 (95% confidence interval [CI], 0.96-3.33; P=0.06). Among subjects randomized to high-dose vitamin A, the odds ratio was 2.80 (95% CI, 1.16-6.74; P=0.02) versus 1.20 (95% CI, 0.45-3.23; P=0.71) in the placebo group. A haplotype including Pro12Ala was also significantly associated with pancreatic cancer risk in all subjects and in subjects randomized to vitamin A. CONCLUSIONS: This analysis presents the first evidence that PPARG may be associated with pancreatic cancer risk, and this candidate gene should be investigated in future, larger studies.

Effect of population trends in body mass index on prostate cancer incidence and mortality in the United States.

Concurrent with increasing prostate cancer incidence and declining prostate cancer mortality in the United States, the prevalence of obesity has been increasing steadily. Several studies have reported that obesity is associated with increased risk of high-grade prostate cancer and prostate cancer mortality, and it is thus likely that the increase in obesity has increased the burden of prostate cancer. In this study, we assess the potential effect of increasing obesity on prostate cancer incidence and mortality. We first estimate obesity-associated relative risks of low- and high-grade prostate cancer using data from the Prostate Cancer Prevention Trial. Then, using obesity prevalence data from the National Health and Nutrition Examination Survey and prostate cancer incidence data from the Surveillance, Epidemiology, and End Results program, we convert annual grade-specific prostate cancer incidence rates into incidence rates conditional on weight category. Next, we combine the conditional incidence rates with the 1980 prevalence rates for each weight category to project annual grade-specific incidence under 1980 obesity levels. We use a simulation model based on observed survival and mortality data to translate the effects of obesity trends on prostate cancer incidence into effects on disease-specific mortality. The predicted increase in obesity prevalence since 1980 increased high-grade prostate cancer incidence by 15.5% and prostate cancer mortality by between 7.0% (under identical survival for obese and nonobese cases) and 23.0% (under different survival for obese and nonobese cases) in 2002. We conclude that increasing obesity prevalence since 1980 has partially obscured declines in prostate cancer mortality.

Differences in survival by histologic type of pancreatic cancer.

OBJECTIVE: Although pancreatic cancer has an extremely high case fatality rate, little is known about differences in mortality by histologic types. We examined median survival and risk of mortality for endocrine pancreatic tumors and two types of exocrine tumors, adenocarcinomas, and mucinous tumors. METHOD: This analysis included 35,276 pancreatic cancer cases reported to the nine population-based cancer registries participating in the Surveillance, Epidemiology, and End Results program from 1973 to 2000. Survival among cases with pancreatic adenocarcinomas, mucinous tumors, and endocrine tumors were compared using Kaplan-Meier plots. Comparative risks of mortality were evaluated using multivariate adjusted Cox regression models. RESULTS: Endocrine pancreatic cancer cases had a median survival of 27 months compared with a median survival of 4 months for adenocarcinoma and mucinous tumor cases. Compared with adenocarcinoma cases, endocrine tumor cases had a 0.28-fold lower risk of mortality [95% confidence interval (95% CI), 0.26-0.30], and mucinous tumor cases had a 0.88-fold lower risk (95% CI, 0.84-0.91). These results were similar for men and women. Within histologic types, advanced tumor stage, older diagnosis age, surgery, and Black race were associated with increased risks of mortality, whereas female sex and more recent year of diagnosis were associated with decreased risks. CONCLUSION: This study confirms the clinical observation that patients with endocrine pancreatic cancer survive longer than patients with exocrine tumors. A better understanding of these differences could contribute to identifying the underlying causes of pancreatic cancer and to improving survival rates across all histologic types.