The 44-year-long study, which originated with 46,022 women in 1968, sought to establish the very long-term risks or benefits associated with use of combined oral contraceptives.
The rates of specific and any cancers were calculated for women who had ‘ever’ and those who had ‘never’ used combined oral contraceptives.
The study found that ‘ever’ use of oral contraceptives was associated with reduced colorectal, endometrial, ovarian and lymphatic and hematopoietic cancer.
An observed increased risk of breast and cervical cancer during current and recent users ‘appeared to be lost’ within approximately five years of stopping oral contraception.
The results further suggest that there is no risk of new cancers appearing later in life among women who had used oral contraceptives.
The researchers concluded: ‘Thus, the overall balance of cancer risk among past users of oral contraceptives was neutral with the increased risks counterbalanced by the endometrial, ovarian, and colorectal cancer benefits that persist at least 30 years.’
RCGP chair Professor Helen Stokes-Lampard said: ‘Millions of women worldwide who use the combined oral contraceptive pill should be reassured by this comprehensive research that they are not at increased risk of cancer as a result – and that taking the pill might actually decrease their risk of certain cancers.
‘This is not to advocate that women should be given the pill as a preventative measure against cancer as we know that a minority of women do have adverse health effects as a result of taking the pill. Ultimately, decisions to prescribe the pill need to be made on a patient-by-patient basis, but this research will be useful to inform the conversations we have with our patients when discussing various contraceptive options that are available.
‘Long-term and ongoing research into the health effects of any medication is important in shaping new clinical guidelines around the care we are able to provide to our patients – and it’s encouraging to hear that RCGP research that originated in in the 1960s is still having a positive impact and increasing our knowledge now.’