To the Editor.
—The article by Dr Davis and associates1 deserves comment. The authors have excluded from "smoking-related cancers" primary cancers of the pancreas, kidney, and bladder. These are increased at least twofold in cigarette smokers compared with nonsmokers.2 If these cancers had been excluded from the "non—smoking-related cancers," there would have been little increase in their incidence since 1900 in Fig 4 of the article.If most non—smoking-related cancers did not increase, why then does the risk of breast cancer increase 2.7-fold in recent cohorts of women, following the 6.5-fold rise of all smoking-related cancers? Smoking-related cancers reached a peak in those born in the 1950s. This observation confirms other reports of the importance of indoor tobacco smoke pollution at home on children and wives. Significant statistical associations exist between the rise of lung cancer mortality in men and increased death rates from breast cancer 20 or