Cancer appears to have overtaken cardiovascular disease (CVD) as a leading cause of death in adults with type 2 diabetes, a 20-year population study in England suggests.
The researchers found that, from 1998 to 2018, in more than 130,000 adults aged 35 and older with type 2 diabetes, all-cause mortality declined for all ages, but cancer mortality increased for those aged 75 and older; people with type 2 diabetes who were smokers had higher and steadily increasing cancer mortality rates; and people with type 2 diabetes had more than twice the rate of colorectal, pancreatic, liver, and endometrial cancer mortality than age- and sex-matched individuals in the general population.
The findings suggest that “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 researchers wrote.
Tailored cancer prevention and early-detection strategies are needed to address persistent inequalities in the older population, the most deprived, and smokers, they added.
Breast cancer rates in younger women with type 2 diabetes rising
According to the researchers, “early cancer detection through changes to existing screening [programs], or more in-depth investigations for suspected/nonspecific symptoms, may reduce the number of avoidable cancer deaths in people with type 2 diabetes.”
Moreover, breast cancer rates in younger women with type 2 diabetes are rising by 4.1% per year, they wrote, which suggests such women are high risk and should be screened at a younger age, but screening age would need to be determined in cost-effectiveness analyses.
The study by Suping Ling, PhD, and colleagues was published online in Diabetologia.
Results challenge belief that preventing CVD is priority in type 2 diabetes
“The prevention of cardiovascular disease has been, and is still considered, a priority in people with diabetes,” the researchers wrote.
“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.”
“The proportion of cancer deaths out of all-cause deaths remains high (> 30%) in young ages, and it was steadily increasing in older ages,” Dr. Ling, from the department of noncommunicable disease epidemiology, London School of Hygiene & Tropical Medicine, said in a comment.
“Combined with previous studies reporting decreasing CVD mortality rates,” she said, “we concluded that cancer might have overtaken CVD as the leading cause of death in people with type 2 diabetes.”
Many evidence-based cancer-prevention strategies related to lifestyle (such as being physically active, being a healthy weight, eating a better diet, stopping smoking, as summarized by the World Cancer Research Fund), are helpful for preventing both cancer and CVD, Ling observed.
However, in the medical community, many additional efforts were made for monitoring, early detection, and innovating medications for CVD, she noted. “Therefore, we would like to propose a similar level of attention and effort for cancer in people with type 2 diabetes.”
Deaths from cancer vs. all causes in patients with diabetes
The researchers identified 137,804 patients aged 35 and older who were newly diagnosed with type 2 diabetes from 1998 to 2018 in general practices in the UK that were part of the Clinical Practice Research Datalink.
Patients were a median age of 64 years and 45% were women. Most (83%) were White, followed by South Asian (3.5%), Black (2.0%), and other (3%); 8.4% had missing information for race. Patients had a median body mass index (BMI) of 30.6 kg/m2.
Researchers divided patients into socioeconomic quintiles of most to least deprived based on income, employment, education, and other factors. During a median follow-up of 8.4 years, there were 39,212 deaths (28.5%).
Cancer mortality in subgroups of patients with type 2 diabetes
Researchers analyzed annual deaths from cancer and from all causes over 20 years in subgroups of patients with type 2 diabetes.
In adults with type 2 diabetes, the average percentage change in cancer mortality per year, from 1998 to 2018 decreased in people aged 55 and 65 (–1.4% and –0.2%, respectively), but increased in people aged 75 and 85 (1.2% and 1.6%, respectively); increased more in women than in men (1.5% vs 1.0%), although women had lower cancer mortality than men; and increased more in the least deprived (wealthiest) individuals than in the most deprived (1.5% vs 1.0%). Cancer mortality rates were consistently higher in the most deprived individuals, Dr. Ling noted.
Cancer mortality also increased more in people with class III obesity (BMI ≥ 35) versus normal weight (5.8% vs 0.7%) and versus other weights. In addition, there was an upward trend in cancer mortality in people who were White or former/current smokers.
Deaths from specific cancers in diabetes vs. general population
Next, researchers determined cancer mortality ratios – the cancer mortality of the patients with diabetes divided by the cancer mortality of the general population.
They determined this for all cancers, the four most common cancers in the United Kingdom (lung, colorectal, breast, and prostate), and cancers caused by type 2 diabetes (pancreatic, liver, gallbladder, and endometrial cancer), standardized by sex and age.
Mortality from all cancer was 18% higher in patients with type 2 diabetes, compared with the general population.
Overall, mortality from colorectal cancer, pancreatic cancer, and liver cancer was 2.4 times, 2.12 times, and 2.13 times higher, respectively, in patients with type 2 diabetes than in the general population.
Mortality from breast cancer was 9% higher and mortality from endometrial cancer was 2.08 times higher in women with type 2 diabetes than in women in the general population.
There was a constant upward trend for 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 study was funded by Hope Against Cancer. Dr. Ling reported no relevant financial relationships.
A version of this article first appeared on Medscape.com.