Roles of radiotherapy and smoking in XXXX following @entity978 .

@entity1 @entity4174 @entity5 @entity2 @entity3700 @entity978
BACKGROUND: Several studies have shown that survivors of @entity978 have increased risk of @entity2 , but the factors responsible for this excess risk are not well known. PURPOSE: This study was undertaken to investigate the effects of radiation dose, chemotherapy, and smoking on the risk of @entity2 following treatment of @entity978 . METHODS: We conducted a case-control study in a cohort of 1939 @entity1 treated for @entity978 from 1966 through 1986 in The Netherlands. Detailed treatment information was collected from the medical records for 30 case @entity1 with @entity2 following @entity978 and 82 matched control subjects who had not developed @entity2 . Multiple sources were used to obtain as complete smoking histories of the study @entity1 as possible. For each case-control set, the radiation dose received by the area of the lung where the case @entity1 developed the @entity5 was estimated on the basis of radiotherapy charts and experimental simulations of treatments. The estimates of relative risk (RR) for @entity2 associated with specific exposures were obtained from logistic regression methods, and all tests of statistical significance were two-sided. RESULTS: A statistically significant increase in risk of @entity2 was observed with increasing radiation dose (P for trend = .01) with an RR of 9.6 (95% confidence interval [CI] = 0.93-98) for @entity1 who received 9 Gy or more compared with those who received less than 1 Gy. @entity1 who smoked more than 10 pack-years after the diagnosis of @entity978 had a sixfold increase in the risk of @entity2 compared with @entity1 who smoked less than 1 pack-year (P = .03). Positive interaction on a multiplicative scale was observed between the carcinogenic effects of smoking and radiation. The increase in risk of @entity2 with increasing radiation dose was much greater among the @entity1 who smoked after diagnosis of @entity978 than among those who refrained from smoking (P = .04). There was no increase in @entity2 risk in relation to the number of cycles of chemotherapy or the cumulative doses of the drugs @entity3700 and @entity4174 . CONCLUSIONS: The excess risk of @entity2 in @entity978 @entity1 treated with radiotherapy is related to the radiation dose received by the affected area of the lung. Smokers experience a significantly greater risk attributable to radiotherapy than nonsmokers. IMPLICATIONS: Physicians in charge of @entity1 treatment should make a special effort to dissuade @entity978 @entity1 from smoking after receiving radiotherapy.
