20-Year Study Finds Cancer Mortality On The Rise People with Type 2 Diabetes

An analysis of 2 decades worth of data from the Clinical Practice Research Datalink suggests all-cause mortality rates in type 2 diabetes have decreased but sheds light on upward trends in mortality from multiple different forms of cancer, including pancreatic, liver, and lung cancer, particularly among older patients.

A study assessing risk of mortality over a 20-year period suggests risk of cancer might one day dethrone cardiovascular disease as the leading health concern for people with type 2 diabetes.

Using data from more than 130,000 individuals with a median follow-up time of more than 8 years, results of the study demonstrate rates of all-cause mortality decreased across all age groups with type 2 diabetes from 1998 to 2018, but also provide evidence of constant upward trends in mortality rates for pancreatic, liver, and lung cancer at all ages, colorectal cancer at most ages, breast cancer at younger ages, and prostate and endometrial cancer at older ages.

“The prevention of cardiovascular disease has been, and is still considered, a priority in people with diabetes. Our results challenge this view by showing that cancer may have overtaken cardiovascular disease as a leading cause of death in people with type 2 diabetes,” wrote investigators. “Cancer prevention strategies therefore deserve at least a similar level of attention as cardiovascular disease prevention, particularly in older people and for some cancers such as liver, colorectal and pancreatic cancer.”

The study, which comes just a few months after an EPIC study analysis found people with type 2 diabetes had an increased risk of advanced stage cancer at time of diagnosis, is the latest addition to a growing evidence base related to cancer in people with diabetes. Led by Suping Ling, PhD, of the Leicester Diabetes Research Centre at the University of Leicester, and funded by Hope Against Cancer, the current study was launched with the specific intent of assessing how rates of cancer mortality in people with type 2 diabetes have changed in recent decades as well as how this risk compares to the general population. With this in mind, investigators designed the current research endeavor as an analysis of data from the Clinical Practice Research Datalink recorded between January 1, 1998 and November 30, 2018 to estimate trends in all-cause, all-cancer, and cancer-specific mortality rates according to age, gender, ethnicity, socioeconomic status, obesity, and smoking status.

From the Clinical Practice Research Datalink, investigators performed a search to identify individuals aged 35 years and older with a first-ever diagnosis of type 2 diabetes, which yielded a total study population of 137,804 individuals with a median follow-up of 8.4 years. For the purpose of analysis, investigators used Poisson regression to calculate age- and calendar year-specific mortality rates and Joinpoint regression to assess trends for each outcome of interest.

Upon analysis, results indicated all-cause mortality rates decreased during the study period at all ages. When examining cancer-related mortality, results suggested mortality rates decreased for 55-year-olds (AAPC, -1.4% [95% CI, -1.5 to -1.3]) and 65-year-olds (AAPC, -0.2% [95% CI, -0.3 to -0.1]), but increased for 75-year-olds (AAPC, 1.2% [95% CI 0.8 to 1.6]) and 85-year-olds (AAPC 1.6% [95% CI, 1.5 to 1.7]). Further analysis revealed increased AAPCs were observed for women relative to their male counterparts (1.5% vs 0.5%), for those least deprived relative to those considered the most deprived (1.5% vs 1.0%), and among those with morbid obesity relative to their counterparts with normal body weight (5.8% vs 0.7%). Further analysis also demonstrated increasing mortality rates from cancer were observed for people of White ethnicity and former/current smokers, but investigators noted downward trends were observed for other ethnic groups and non-smokers, which they purport has contributed to persistent inequalities by gender and deprivation but widening disparities by smoking status.

When stratifying by type of cancer, results indicated constant upward trends in mortality rates were recorded for pancreatic, liver and lung cancer at all ages, colorectal cancer at most ages, breast cancer at younger ages, and prostate and endometrial cancer at older ages. Investigators called attention to additional results of interest, specifically a more than 1.5-fold increased risk of colorectal, pancreatic, liver, and endometrial cancer mortality for people with type 2 diabetes relative to the general population, which was evident throughout the study period.

“Our findings underline the growing cancer burden in people with type 2 diabetes, particularly in older individuals, and highlight the need to prioritise cancer prevention, research and early detection and management in this population, especially for colorectal, pancreatic, liver and endometrial cancer, whose mortality rates were substantially higher in individuals with type 2 diabetes than in the general population,” investigators concluded.

This study, “Inequalities in cancer mortality trends in people with type 2 diabetes: 20 year population-based study in England,” was published in Diabetologia.