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pubmed:otherAbstract |
PIP: Guidelines for prescribing oral contraceptives (Ocs), which take into account recent research findings concerning the relationship between OC use and the development of cervical and breast neoplasia and vascular diseases, were suggested. The findings of M.P. Vessey and his colleagues that the risk of cervical neoplasia increases with the duration of OC use are difficult to interpret. OC is strongly associated with certain types of sexual behavior, e.g., initiation of sexual activity at an early age, frequent intercourse, and intercourse with multiple partners, and these behavioral factors, in turn, are known to be associated with an increased risk of cervical cancer. Although an attempt was made to control for the effects of these behavioral factors, the findings of the study require further substantiation. Even if the findings are correct, OC users would appear to have only a minor excess risk of developing invasive carcinoma, and even this minimal increased risk could be avoided encouraging OC users to have cervical smears taken routinely. The findings of Pike and his colleagues in California concerning the risk of breast cancer among OC users are more controversial, and potentially more serious. The study found that there was a 4-fold increased risk of breast cancer in women, under the age of 37, who had used OCs prior to their 25th birthday, and the risk increased with duration of OC use. A study by McPerson and colleagues also reported that breast cancer was associated with the duration of OC use prior to 1st pregnancy. Other intensive studies have failed to reveal a relationship between breast neoplasia and OC use. Pike and his colleagues also published a table listing OC brands in rank order of their progestogen potency. Pike noted that there was a positive relationship between the occurrence of breast cancer and the level of progestogen potency. The table was harshly criticized because it is not possible to determine the potency level of combined formulations. Nevertheless, those brands associated with a higher risk of breast cancer contained high doses of progestogen as well as estrogen, and their use should be avoided. Furthermore, OCs with high progestogen doses should be avoided in order to reduce the risk of vascular diseases among OC users. The RCGP study demonstrated that there is a positive relationship between progestogen dosage and the development of arteriosclerotic diseases. OC formulations with doses exceeding 1 mg of norethisterone acetate and 150 mcg of levonorgestrel should be avoided. Breakthrough bleeding should be controlled by increasing the estrogen dose to 50 mcg rather than by altering the progesterone level. Effort should also be made to carefully tailor OC prescribing to the specific needs of each patient. The risk of vascular diseases among OC users is almost exclusively confined to older women who smoke. Care must be exercised in prescribing OCs for women who smoke and for women who other characteristics that place them at high risk of developing vascular disease. Since women differ considerably in the way they utilize and metabolize the steroids contained in OCs, efforts should be made to develop an inexpensive and simple technique for measuring serum steriod levels. This would allow physicians to reduce the steriod content of OCs for those women whose systems make maximal use of available steriods.
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