Radiation and Smoking Effects on Lung Cancer Incidence by Histological Types Among Atomic Bomb Survivors

Abstract

While the risk of lung cancer associated separately with smoking and radiation exposure has been widely reported, it is not clear how smoking and radiation together contribute to the risk of specific lung cancer histological types. With individual smoking histories and radiation dose estimates, we characterized the joint effects of radiation and smoking on type-specific lung cancer rates among the Life Span Study cohort of Japanese atomic bomb survivors. Among 105,404 cohort subjects followed between 1958 and 1999, 1,803 first primary lung cancer incident cases were diagnosed and classified by histological type. Poisson regression methods were used to estimate excess relative risks under several interaction models. Adenocarcinoma (636 cases), squamous-cell carcinoma (330) and small-cell carcinoma (194) made up 90% of the cases with known histology. Both smoking and radiation exposure significantly increased the risk of each major lung cancer histological type. Smoking-associated excess relative risks were significantly larger for small-cell and squamous-cell carcinomas than for adenocarcinoma. The gender-averaged excess relative risks per 1 Gy of radiation (for never-smokers at age 70 after radiation exposure at age 30) were estimated as 1.49 (95% confidence interval 0.1–4.6) for small-cell carcinoma, 0.75 (0.3–1.3) for adenocarcinoma, and 0.27 (0–1.5) for squamous-cell carcinoma. Under a model allowing radiation effects to vary with levels of smoking, the nature of the joint effect of smoking and radiation showed a similar pattern for different histological types in which the radiation-associated excess relative risk tended to be larger for moderate smokers than for heavy smokers. However, in contrast to analyses of all lung cancers as a group, such complicated interactions did not describe the data significantly better than either simple additive or multiplicative interaction models for any of the type-specific analyses.

Lung, Laryngeal and Other Respiratory Cancer Incidence among Japanese Atomic Bomb Survivors: An Updated Analysis from 1958 through 2009

“…For lung cancer, the ERR/Gy increases with smoking up to approximately 10 cigarettes per day and then decreases, approaching no radiation-associated excess risk for subjects who smoke 20 or more cigarettes per day, a similar pattern was found in previously reported work (1, 2, 8). In the moderate smoking intensity range near 10 cigarettes per day, smoking could promote radiation-initiated cells by causing inflammation in the tissue microenvironment (9).…”

“…However, a sensitivity analyses, which discounted smoking duration over the period of follow-up when smoking was unknown, suggests that the radiation effect and smoking-radiation effect modification were not particularly sensitive to the incompleteness of the smoking history data. In the current analysis, we considered all lung cancer types together, while smoking and radiation have different effects on different subtypes of lung cancer (2). However, it should be noted that the nature of the joint effects of smoking and radiation showed a similar pattern for different types of lung cancer (2).…”

“…Incidence of lung cancer, which is the second most common cancer in the LSS, has been most recently examined using follow-up through the year 1999 (1, 2). Furukawa and colleagues reported a sex-averaged excess relative risk per Gy (ERR/Gy) of lung cancer (at age 70 after radiation exposure at age 30) to be 0.59 (95% CI: 0.31–1.00) for nonsmokers with a female-to-male ratio of 3.1 (1).…”

Cancer risk at low doses of ionizing radiation: artificial neural networks inference from atomic bomb survivors

“…ADR is also inducible in spermatogonial cells of mice, but it is not transmitted to offspring [131]. In A-bomb survivors, radiation exposure influences the risk of lung cancer associated with tobacco smoking, including post-bombing smoking history, where the joint effects are less than additive; in this way it has been reported that radiation exposure tends to decrease the risk of smoking-associated lung cancer more efficiently in heavier smokers [133–135]. A more pronounced effect of radiation exposure on heavier smokers is likely because the repair mechanism depends on the types and amount of damage in the genome.…”

16 Comparison of clinicopathological features and prognosis in prostate cancer between atomic bomb survivors and control patients

“…The pattern of radiation-related risks for solid cancer exhibits a gradual increase starting several years after the bombings, while the risk of leukemia increased in the early period immediately subsequent to the bombing, and then decreased (4,5). Although the clinicopathological features of several types of cancer have been investigated in these survivors (6)(7)(8), there are only a small number of studies on the clinicopathological features of urological cancer. To the best of our knowledge, there has been no report about the features of prostate cancer (PCa) in A-bomb survivors.…”