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Women with Diabetes at Higher Risk for Certain Cancers

Sep 8, 2018
 

Women with diabetes are at higher risk for oral cancer, kidney cancer, stomach cancer, and leukemia than their male counterparts, a new study shows.

Women with diabetes may now have something additional to be concerned about: cancer. Past epidemiological studies have already tied the link between type 2 diabetes and an increased risk of developing different types of cancer, such as liver, colon, and breast cancer. Differentiating this risk between sex, however, is relatively new and not extensively studied.

Researchers, in a new study published May of 2018, focused on determining whether diabetes carries the same overall risk in men and women for developing certain types of cancer. According to the investigators, no other study to date had utilized a systematic overview of prior evidence to find a link between sex differences and risk for cancer in patients with diabetes.

The study was performed as a systematic review of 121 observational cohorts, which included data on the risk for cancer in more than 19 million men and women with diabetes. Studies were included only if results were posed as relative risk (RR) or similar presentation to show the link between diabetes and cancer in men and women. Studies that did not adjust for age, provide data on variability around the point estimate, or gave data only for one sex, were excluded from the analysis. For each study, investigators examined the RR and 95% confidence intervals (CIs) to analyze the sex-specific differences in relation to risk of cancer.

When investigators examined the data, they found that the risk of cancer for women with diabetes was indeed greater than that of men. For both fatal and non-fatal cancers combined, the RR for women was 1.27 (p<0.001), whereas for men they found the RR to be 1.19 (p<0.001). This did not vary significantly for type of diabetes.

Investigators also looked at data on risk of cancer in specific sites in men vs. women, finding a statistically significant increased risk of cancer in 20 sites in women vs. 18 sites in men. When a relative risk ratio (RRR) was calculated for women-to-men, it was observed that the RRR was significantly greater in women than men for oral cancer, renal cancer, stomach cancer, and leukemia. Individual results are shown below.

Type of Cancer Relative Risk Ratio P value
Oral 1.13 [1.00, 1.28] 0.009
Kidney 1.11 [1.04, 1.18] < 0.001
Stomach 1.14 [1.07, 1.22] < 0.001
Leukemia 1.15 [1.02, 1.28] 0.002

Overall, the results of this meta-analysis were compelling given that this study was the largest of its kind to delve into such a topic. While one other previous study examined the link between cancer risk for patients with diabetes, investigators of this study noted that this meta analysis was the first, and largest, study to examine the sex-differences in relation to cancer risk. The investigators concluded that based on the results, women showed a 6% higher risk of cancer overall compared with men, and the risk for certain types of cancer was also greater.

While the reason for this risk may remain unknown, scientists believe it could be due to women having poorer glycemic control than men. This  leads to prolonged periods of hyperglycemia, which has been tied to carcinogenic effects due to oxidative stress on DNA. They also link this possibility to a lack of proper treatment for women with diabetes, as well as a lack of adherence to diabetes medications. Whatever the cause may be, it is safe to say that as the number of patients with pre-diabetes and diabetes continues to rise, more sex-specific research should be done to definitively tie a link between cancer and diabetes.

Practice Pearls:

  • Among the 19 million individuals studied, women with diabetes showed a 6% greater risk of developing cancer compared with men.
  • In regards to specific types of cancer, women with diabetes are at higher risk for oral cancer, kidney cancer, stomach cancer, and leukemia than their male counterparts.
  • While the risk for women with diabetes developing all-site cancer in general was higher, men showed a greater risk for developing liver cancer compared with women.

Reference:  

Ohkuma, T., Peters, S. A., & Woodward, M. (2018). Sex differences in the association between diabetes and cancer: A systematic review and meta-analysis of 121 cohorts including 20 million individuals and one million events. Diabetologia,1-15. doi:10.1007/s00125-018-4664-5

Clarke Powell, Pharm.D. Candidate 2019, LECOM School of Pharmacy