Oral Contraceptives (which increase Vitamin D) reduce the risk of some cancers

Created January 2018

“ . . the effect is especially evident in smokers, the obese and those who exercise infrequently. .
- These people are at high risk of being Vitamin D deficient
“… those who had used them for 10 years or more had a 34 percent reduced risk for endometrial cancer…”
“Contraceptive use did not seem to affect the risk for postmenopausal colorectal or breast cancer.”

Results (from the JAMA abstract) doi:10.1001/jamaoncol.2017.4942

The analytic population was aged 50 to 71 years (median, 62 years) at enrollment and largely white (91%) and postmenopausal (96%). For

ovarian cancer, OC use–associated risk reductions strengthened with duration of use (long-term OC use [≥10 years] HR, 0.60; 95% CI, 0.47-0.76; P < .001 for trend) and were similar across modifiable lifestyle factors.
Risk reductions for endometrial cancer strengthened with duration of use (long-term OC use HR, 0.66; 95% CI, 0.56-0.78; P < .001 for trend);
the most pronounced reductions were among long-term OC users who were
- smokers (HR, 0.47; 95% CI, 0.25-0.88), had
- obese BMIs (0.36; 95% CI, 0.25-0.52), and who
- exercised rarely (HR, 0.40; 95% CI, 0.29-0.56).
Associations between OC use and breast and colorectal cancers were predominantly null.

Note by VitaminDWikik – breast and colorectal cancers usually do not start until years after contraceptives are stopped