The relationship between dietary factors and the risk of breast cancer was investigated ina case-control study conducted in the Canton of Vaud, Switzerland as a pilot phase for a larger cooperative study within the SEARCH Programme of the International Agency for Research on Cancer (Lyon, France). A total of 107 incident, histologically confirmed cases of breast cancer and 318 controls admitted to hospital for acute, nonhormone-related, gynecological, metabolic, or neoplastic disorders were interviewed. Significant direct trends in risk were observed with total energy intake [relative risk (RR) for highest vs. lowest intake tertile = 1.9] and, after allowance for energy intake, with frequency of consumption of various types of meat (RR = 2.1 for the highest tertile), cheese (RR = 2.7), and alcohol (RR = 2.1). Significant protections, on the order of 40-60% reductions for the highest vs. lowest consumption tertile, were conferred by total green vegetable consumption, selected types of vegetables and fruits (cucumbers, onions, pears), and a summary index of β-carotene intake (RR = 0.4 for highest consumption tertile). Thus the present study confirmed the existence of an unfavorable dietary pattern for breast cancer risk (characterizedby high-calorie, selected sources of animal fat and alcohol intake). Moreover, a significant protection could be gained by consuming a diet rich in vegetables and perhaps fruits.

We conducted a study on 91 women with thyroid cancer and 306 controls in hospital for acute nonneoplastic, non-hormone-related disorders in order to investigate the role of reproductive and hormonal factors in the etiology of epithelial thyroid cancer in the Canton of Vaud, Switzerland. Non-significant increases in cancer risk with an increasing number of full-term pregnancies (odds ratio, OR, after allowance for age and previous benign thyroid disease = 1.6, for > 3 vs. 0 full-term pregnancies, 95% confidence interval, CI: 0.7–3.6) and spontaneous abortions (OR = 2.0 for > 2 vs. 0 spontaneous abortions, 95% CI: 0.7–5.2) were seen. A significantly elevated OR (2.8,95% CI: 1.1–7.2) was found in those women whose first pregnancy ended with an abortion. Whereas most other reproductive, menstrual and hormonal factors examined did not seem to affect the risk of thyroid cancer significantly, a clue emerged of an association between thyroid cancer and artificial menopause (OR = 6.3, for women who underwent artificial menopause vs. premenopausal women, 95% CI: 1.7–23.2). Although not necessarily causal, the relationship between the risk of epithelial thyroid cancer and the occurrence of spontaneous abortions and artificial menopause deserves attention in future studies, in the light of the high incidence of thyroid cancer in young and middle-aged women.

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The relationship between the use of combination oral contraceptives (OCs) and the risk of endometrial cancer was assessed in a case-control study conducted in the Swiss Canton of Vaud between 1 January 1988 and 31 July 1990. Subjects included 122 women aged 75 or less with histologically confirmed endometrial cancer, and 309 control women in hospital for acute conditions unrelated to OC use. Overall, 14 percent of cases and 27 percent of controls had ever used OCs, corresponding to a multivariate relative risk (RR) of 0.5 (95 percent confidence interval [CI]: 0.3, 0.8). The risk of endometrial cancer was found to be related inversely to duration of OC use: RR = 1.0 for less than two years of OC use; 0.5 for two to five years; and 0.3 (95 percent CI: 0.1, 0.7) for more than five years. The protection appeared greater within 20 years since last use, and the RR rose to 0.8 after 20 or more years since last use; numbers are too small, however, for reliable inference from these subanalyses. No significant interaction or modifying effect was observed with other major factors related to endometrial cancer, including parity, body mass index, estrogen replacement therapy, and cigarette smoking. While this study provides further evidence for the protective effect of OCs against risk of endometrial cancer, the relationship requires continued evaluation to assess the long-term implications and public health impact of OC use.

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