Breast cancer in first-degree relatives and risk of lung cancer: assessment of the existence of gene sex interactions.
BACKGROUND
Previous studies have shown the sex differences in lung cancer and the associations between estrogen-related genes and non-small cell lung cancer. In the present study, we assumed the existence of shared candidate genes that are common in lung and breast cancers, and examined whether women with a family history of breast cancer are at increased risk of lung cancer compared with men, especially adenocarcinoma, in a case-only study.


METHODS
This case-only study was conducted based on the Lung Cancer Database Project at the National Cancer Center Hospital East. A total of 1566 patients with newly diagnosed primary lung cancer were consecutively recruited between 1999 and 2003. Information on their family history of cancer and smoking habit was obtained from a self-administered questionnaire. To assess an interactions between two factors, odds ratios for interaction (ORis) and 95% confidence intervals (CIs) were calculated by case-only contingency table.


RESULTS
A statistically significant ORi was observed between a family history of breast cancer in first-degree relatives (parent and siblings, not including children) and the sex of a patient (ORi: 2.22, 95% CI: 1.02-4.81). A stratified analysis by histologic subtypes showed a statistically significant ORi only for adenocarcinoma (ORi: 3.27, 95% CI: 1.19-8.98). No other family history of cancer, such as stomach, colon and lung cancer, showed a statistically significant ORi.


CONCLUSIONS
This study suggests the possibility of gene-sex interaction in lung cancer.
Tsuchiya
Masaki
M
Epidemiology and Prevention Division, Research Center for Cancer Prevention and Screening, National Cancer Center, Tokyo, Japan.
Iwasaki
Motoki
M
Otani
Tetsuya
T
Nitadori
Jun-ichi
J
Goto
Koichi
K
Nishiwaki
Yutaka
Y
Uchitomi
Yosuke
Y
Tsugane
Shoichiro
S
D000230:Adenocarcinoma / Q000235:genetics*; D001943:Breast Neoplasms / Q000235:genetics*; D002289:Carcinoma, Non-Small-Cell Lung / Q000235:genetics*; D005190:Family; D005260:Female; D006801:Humans; D008175:Lung Neoplasms / Q000235:genetics*; D008297:Male; D008875:Middle Aged; D012737:Sex Factors; D012907:Smoking / Q000009:adverse effects