Higher Obesity-Related Cancer Risk in Women With Type 2 Diabetes

Women diagnosed with type 2 diabetes (T2D) may be at a higher risk for developing cancer as early as 5 years before receiving a diagnosis of diabetes when compared with women in the general population, while men and women may be at a higher risk for receiving a diagnosis of cancer in the years following a diagnosis of diabetes, according to a study published in PLOS One.

Researchers identified 69,583 individuals (49% women) from 2 prospective cohort studies (Zwolle Outpatient Diabetes project Integrating Available Care and the Netherlands Cancer Registry) linked with the Dutch National Cancer registry and assessed the association between the diagnosis of T2D and the incidence of obesity-related cancer in both men and women diagnosed with T2D compared with the general Dutch population in the 5 years preceding, the year after, and the 4 years following diagnosis.

Study results found the highest incidence of cancer diagnosis in both men and women diagnosed with T2D occurred during the first year following the T2D diagnosis (standardized incidence ratio [SIR] 1.80; 95% CI 1.59-2.01), with elevated levels of cancer diagnosis also found in the 5 years prior and 2 to 5 years after being diagnosed with T2D compared with the general Dutch population.

In women diagnosed with T2D, there was a significantly increased incidence of obesity-related cancer 5 years before a diagnosis of diabetes (SIR 1.86; 95% CI 1.37-2.00), which dropped significantly the year before a T2D diagnosis (SIR 1.44; 95% CI, 1.17-1.70), followed by the highest incidence 1 year after diagnosis (SIR 2.21; 95%CI 1.88-2.54) that remained increased for the remaining 5 years after a T2D diagnosis.

Men did not demonstrate a significant increase in cancer diagnosis incidence in years 5 to 1 before a T2D diagnosis, with significant increases only seen in the year before (SIR 1.32; 95% CI 1.06-1.58) and year after (SIR 1.38; 95% CI 1.11-1.64) T2D diagnosis when compared with the general Dutch population. 

Finally, when researchers examined the influence on a T2D on sex-specific cancers, it found that women had an elevated SIR at all points of time with the same noted decrease the year prior to T2D diagnosis when examining breast cancer alone, while in men there was a decreased incidence of prostate cancer in the 5 years preceding a diagnosis of T2D, but no difference in incidence in the years after diagnosis.

Researchers concluded that the peak incidence level of cancer diagnosis occurred in the year after being diagnosed with T2D, with a clear difference in cancer risk noted between men and women.  When compared with the general population, both men and women had an increased incidence of obesity-related cancer diagnosis in the years after diabetes diagnosis, with a more pronounced increase in women.

However, women also had an increased incidence of obesity-related cancers as early as 5 years before being diagnosed with T2D.  When sex-specific cancers were excluded from the analysis, women had a lower incidence of cancer, while men had a higher SIR.  Results appear to demonstrate a protective factor present in the general population of women that disappears with obesity and the diagnosis of diabetes compared with men.

Reference

Schrijnders D, Hendricks SH, Kleefstra N, et al. Sex differences in obesity related cancer incidence in relation to type 2 diabetes diagnosis (ZODIAC-49) [published online January 25, 2018]. PLOS One. doi:10.1371/journal.pone.0190870