INCREASED FAMILIAL RISK FOR NON-LUNG CANCER AMONG RELATWES OF LUNG CANCER PATIENTS

Abstract

Reports of two or more anatomically distinct cancer types clustering in families suggest the possible existence of a susceptibility-to-cancer gene. To determine whether a genetic predisposition accounts for such familial aggregation, a ret rospective case-control study was conducted in 1976–1979 of 337 southern Louisiana families in each of which a deceased lung cancer patient was used as the proband. A comparison of first-degree relatives of proband families with spouse (control) families revealed a significantly greater overall risk of cancer (odds ratio (OR) = 2·0, p < 0·0001) in the proband group. Using logistic regression techniques to control for the confounding effects of age, so; cigarette smoking, and occupational/Industrial exposures, relatives of lung cancer probands main tained an increased risk of non-lung cancer (p < 0·05). The crude odds ratio of a proband family having one family member with cancer was 1·67 compared with control families. Proband families were 2·16 times more likely to have two other family members with cancer. For three cancers and four or more cancers, the risk increased to 3·66 and 5·04, respectively. Each risk estimate was significant at the 0·01 level. The most striking differences in cancer prevalence between proband and control families were noted for cancer of the nasal cavity/sinus, mid-ear, and larynx (OR = 4·6); trachea, bronchus and lung (OR = 3·0); skin (OR = 2·8); and uterus, placenta, ovary, and other female organs (OR = 2·1). These data support the hypothesis of a genetic susceptibility to cancer in families with lung cancer.