Long-term benefits of OCs in cancer prevention

August 12, 2015

A new study indicates that oral contraceptives may have benefits beyond the reproductive. And, does vitamin D really provide a benefit in postmenopause? Plus: do cranberry capsules reduce the number of post-surgical UTIs?

In addition to their reproductive benefits, oral contraceptives (OCs) provide long-term protection against endometrial cancer, according to a new meta-analysis in The Lancet of data from 36 epidemiological studies. The findings suggest that, over the past 50 years in developed countries, OCs have prevented 400,000 cases of the disease in women younger than age 75.

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Researchers from the Collaborative Group on Epidemiological Studies on Endometrial Cancer assessed individual information from the 36 studies on 27,276 women who had endometrial cancer and 115,743 women who didn’t have the cancer and served as controls. Logistic regression was used to estimate the relative risks of endometrial cancer associated with OC use. Among the cases, the median age was 63 years and the median year of cancer diagnosis was 2001.

Overall, 9459 of the cases and 45,625 of the controls had any history of using OCs, with a median duration of 3.0 years for the cases and 4.4 years for the controls. The research showed that the longer a woman used OCs, the greater the reduction in her risk of endometrial cancer. Every 5 years of OC use was linked to a risk ratio (RR) of 0.76 (95% CI 0.73-0.78; P < 0.0001). The risk reduction persisted for more than 3 decades after OC use ceased and the RRs did not decline during the 1960s, 1970s, and 1980s, even as the estrogen doses in OCs was reduced.

Risk reduction did differ by tumor type. It was stronger in sarcomas (RR 0.69; 95% CI 0.66 – 0.71) than it was in sarcomas (RR 0.83; 95% CI 0.67 – 1.04; case-case comparison P = 0.02). In high-income countries, a history of 10 years of OC use was estimated to reduce the absolute risk of endometrial cancer arising before age 75 years from 2.3 to 1.3 per 100 women.

Of the roughly 400,000 cases of endometrial cancer in women before age 75 that the investigators believe have been prevented by OC use from 1965 to 2014, half would have occurred in the past decade alone.

NEXT: Does vitamin D provide any postmenopause benefit?

 

Is vitamin D supplementation really beneficial in postmenopause?

Results of a single-center study published in JAMA Internal Medicine suggest that achieving high calcium levels in postmenopause may not equate with clinical bone benefits. The findings, by investigators from the University of Wisconsin, run counter to expert recommendations for shooting for serum 25 (OD)D levels of 30 ng/mL or higher in postmenopausal women.

The randomized, double-blind, placebo-controlled trial was conducted from May 1, 2010 to July 31, 2013 and enrolled 230 postmenopausal women aged 75 or younger with baseline 25(OH)D levels  of 14 to 27 ng/mL who did not have osteoporosis. The objective was to compare the effects of placebo and low- and high-dose calcium on 1-year changes in total fractional calcium absorption, bone mineral density (BMD), Timed Up and Go and 5 sit-to-stand tests, and muscle mass in postmenopausal women with vitamin D insufficiency.

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Seventy-six of the women took daily white and twice-monthly yellow placebo, 75 took 800 IU of vitamin D3 daily and a yellow placebo twice monthly, and 79 of the women took a white placebo daily and 50,000 IU of vitamin D3 twice a month. The high-dose vitamin D regimen achieved and maintained 25(OH)D levels of ≥30 ng/mL.

To assess the impact of 1 year of therapy with placebo or low- or high-dose calcium supplementation, the investigators measured total fractional calcium absorption using 2 stable isotopes, BMD and muscle mass using dual energy x-ray absorptiometry, Timed Up and Go and 5 sit-to-stand tests, a questionnaire on functional status, and scores on physical activity scale for the elderly.

After controlling for baseline absorption, the authors found that calcium absorption increased 1% (10 mg/d) in the women who had been taking high-dose calcium and decreased 2% in those on low-dose calcium (P=.005 versus high-dose arm) and in those on placebo (P=.03 versus high-dose arm arm). There were no differences between the study arms in spine, mean total-hip, mean femoral neck, or total BMD, trabecular bone score, muscle mass, or Time Up and Go or the 5 sit-to-stand test scores. Administration of calcium also made no difference in the number of falls a woman had, the number of women who fell, or the participants’ physical activity or functional status.

The authors concluded that taking high-dose calcium increased calcium absorption but had no beneficial effects on BMD, muscle function, muscle mass, or falls. They found “no data to support experts’ recommendations to maintain serum 25(OH)D levels of 30 ng/mL or higher in postmenopausal women.”

NEXT: Do cranberry capsules reduce risk of post-surigcal UTIs?

 

Reducing post-surgery UTIs with cranberry

Taking cranberry extract capsules after gynecologic surgery that involves urinary catheterization may cut a patient’s risk of urinary tract infection (UTI) by as much as half, according to results of a small new study. The research, by investigators in Michigan, is the first double-blind randomized clinical trial to demonstrate the efficacy of the approach.

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Women participating in the trial ranged in age from 23 to 88 and were recruited from the Urogynecology and Minimally Invasive Surgery clinics of the University of Michigan Division of Gynecology between August 2011 and January 2013. All of their surgeries were elective gynecologic procedures. Among the exclusions were a history of nephrolithiasis and surgery involving fistula repair or vaginal mesh removal.

A total of 160 participants were randomized to receive either 2 cranberry juice capsules twice a day (equivalent to 2 8-oz servings of cranberry juice) or a placebo for 6 weeks following surgery. The primary endpoint was the proportion of participants who experienced clinically diagnosed and treated UTI, which may or may not have been associated with a positive urine culture.

Overall the occurrence of UTI was much lower in the group treated with cranberry extract (5 out of 80) than in the placebo group (30 out of 80) (odds ratio [OR], 0.38; 95% CI, 0.19–0.79; P = .008). Even after adjusting for known confounders, including the frequency of intermittent self-catheterization in the postoperative period, the protective nature of the cranberry juice extract remained (OR, 0.42; 95% CI, 0.18–0.94).

No treatment differences were seen in the incidence of adverse events, including gastrointestinal upset (56% vs 61% for cranberry vs placebo).

The investigators concluded that consuming cranberry extract capsules during the postoperative period seems to reduce the rate of UTI by roughly 50%.