The second type of OC available in the United States is called the minipill and contains only a progestogen. The minipill is less effective in preventing pregnancy than the combination pill, so it is prescribed less often.
Because medical research suggests that cancers of the female reproductive organs sometimes depend on naturally occurring sex hormones for their development and growth, scientists have been investigating a possible link between OC use and cancer risk. In the past 18 years, medical researchers have focused a great deal of attention on OC users. This scrutiny has produced a wealth of data on OC use and the development of certain cancers, although results have not always been consistent.