Thromboembolism, Cancer, and Oral Contraceptives

In each of 5 investigations reported by others regarding thromboembolism attention was concentrated on episodes occurring unexpectedly and in the absence of any evident predisposing cause. Superficial thrombophlebitis risk was increased 3-fold by the use of oral contraceptives. Deep-vein thrombosis and pulmonary embolism were increased 3-11 times by the use of these drugs the best estimate being 6 times. Surgery has been reported as increasing the risk 4-6 times. Discontinuing the use of oral contraceptives 4 weeks before surgery is recommended wherever possible. Estrogens in large doses given to suppress lactation appear to be a factor in the causation of puerperal thromboembolism. Estrogens given to men with arterial disease or prostate cancer have been implicated as a cause of thromboembolism. Oral contraceptives increase the circulatory levels of some blood coagulation factors and alter platelet behavior. Distinctive vascular lesions have been found in women dying from thromboembolism while using oral contraceptives. Compounds containing more than 50 mcg of estrogen are not advised. Restrospective studies indicate that the increased risk of thromboembolism occurs only while oral contraceptives are actually in use except possibly for the first few weeks after discontinuation. Genetic factors may also be of importance. Persons belonging to blood groups A B and AB have an increased risk. Studies suggest that oral contraceptives increase the risk of thrombotic stroke about 6 times. The risk of hemorrhagic stroke is also increased about 2 times. Incidence of hypertension is increased although the risk of myocardial infarction seems not to be increased. As human carcinogens seldom produce an overt effect in less than 10 years firm conclusions cannot be drawn for several more years regarding cancer. In the case of breast cancer early use of these preparations could be beneficial rather than harmful. However in males this may not apply. Chronic cystic breast disease may be less frequent in females using oral contraceptives. No association has been found between use of oral contraceptives and cervical neoplasia or cancers elsewhere. However the administration of stilbestrol to women during pregnancy has been reported to increase the risk of vaginal carcinoma in the offspring who had been exposed in utero to the steroid.