Education and cancer risk.

BACKGROUND

Socioeconomic factors have been associated, to a variable degree, with the risk of serious cancers.

METHODS

The relationship between education and cancer risk was analyzed using data from a series of case-control studies conducted in northern Italy between 1983 and 1990, including 119 histologically confirmed cancers of the oral cavity and pharynx, 294 of the esophagus, 564 of the stomach, 673 of the colon, 406 of the rectum, 258 of the liver, 41 of the gallbladder, 303 of the pancreas, 149 of the larynx, 2860 of the breast, 692 of the cervix, 567 of the corpus uteri, 742 of the ovary, 107 of the prostate, 365 of the bladder, 147 of the kidney, and 120 of the thyroid, 72 Hodgkin diseases, 173 non-Hodgkin lymphomas, 117 myelomas, and a total of 6147 control subjects admitted to the same network of hospitals for acute, non-neoplastic conditions.

RESULTS

Nine types of cancer were inversely related to education. Those were oral cavity and pharynx, with a relative risk (RR) of 0.3 for the highest versus the lowest level; esophagus, RR = 0.6; stomach, RR = 0.5; liver, RR = 0.7; gallbladder, RR = 0.5; larynx, RR = 0.3; cervix, RR = 0.7; endometrium, RR = 0.5; and non-Hodgkin lymphomas, RR = 0.6. Five cancer sites were directly related to education: colon, RR = 1.3; pancreas, RR = 1.3; breast, RR = 1.5; kidney, RR = 1.3; and thyroid, RR = 1.5. No consistent gradient in risk with education was observed for the six other neoplasms considered, including rectum, prostate, bladder, Hodgkin disease, and multiple myeloma. The patterns of risk for education were consistent in men and women for most cancer sites except colon, for which the direct relationship was stronger in males.

CONCLUSIONS

This study confirms the existence of and quantifies a number of strong socioeconomic correlates of cancer risk and indicates a few points open to additional investigation, such as the different pattern of risk for rectal and colon cancer, the strong negative gradient for endometrial cancer, and the absence of any clear association with education for cancers of the ovary, prostate, urinary tract, lymphomas, and myeloma.