In a retrospective analysis of more than 36,000 patients with colon cancer, investigators showed that those with early-stage disease and diabetes or hypertension have a greater risk of recurrence and of dying compared with early-stage patients who do not have either condition.
Diabetes and hypertension are two components of metabolic syndrome, which has been linked to colon cancer. The latest results build on previous studies by suggesting that “patients with early-stage colon cancer who also have diabetes or hypertension may need to be followed more closely for recurrence and could potentially benefit from broader use of adjuvant chemotherapy,” Nestor Esnaola, MD, MPH, MBA, chief of the Division of Surgical Oncology and professor in the Department of Surgery at Temple University School of Medicine in Philadelphia, said in a news release.
Metabolic syndrome is a cluster of conditions that affects one in five American adults and can include diabetes, obesity, hypertension and low levels of good cholesterol and high amounts of lipids in the blood.
To better understand the effect of metabolic syndrome on colon cancer outcomes, Esnaola and his team linked data from the National Cancer Institutes Surveillance, Epidemiology and End Results program, a large population-based database, to Medicare data from 1998 to 2006 on 36,079 patients with colon cancer, including 7,024 patients (19.5%) who were identified as having metabolic syndrome.
The researchers analyzed the effect of metabolic syndrome and its components on colon cancer recurrence and overall survival, controlling for various sociodemographic factors, tumor factors, other medical conditions and cancer treatment received.
“Metabolic syndrome as a whole had no apparent effect on colon cancer recurrence or survival,” said Esnaola, who also is an attending surgeon at Fox Chase Cancer Center in Philadelphia. “When we teased out and analyzed the effect of each of its components, however, the data told a different story.”
The researchers found that among patients with early-stage disease, those with diabetes or hypertension had a significantly greater risk of cancer recurrence rate and death after treatment. For example, 47.7% of patients who did not have diabetes were still alive five years after diagnosis, compared with 41.3% of patients with diabetes. When the researchers looked more closely, they also found that cancer recurrence rates at five years were approximately 8% higher in patients with diabetes or hypertension.
In contrast, the analysis showed that patients with abnormally high levels of lipids in the blood actually had a lower risk of recurrence and death from colon cancer. Overall, 39% of patients with normal lipid levels were still alive after five years, compared with 52.7% of patients with abnormal levels. Cancer recurrence rates were approximately 11 percentage points lower in patients with abnormal lipid levels.
“Although we did not have data medication for these patients, we suspect that the higher survival and lower recurrence rates observed in patients with high lipid levels in our study groups were likely due to the protective effects of statins,” Esnaola said.
“To our knowledge, this is the largest study to date controlling for cancer stage and treatment that has analyzed the effect of metabolic syndrome and its components on colon cancer recurrence and survival,” Esnaola added. “The adverse effects of diabetes and hypertension in early-stage patients and apparent protective effect of high blood lipids observed in our cohort suggest that when it comes to metabolic syndrome and cancer outcomes, the devil is in the details.”
Esnaola is investigating the effect of metabolic syndrome and its components on other cancer types, and plans to confirm these results in a larger set of data that contains information on cancer stage, treatment and medication. “In the interim, our results underscore the need for clinical trials to define the true benefits of metformin [a diabetes drug]and statins in patients with early-stage colon cancer.”
The study abstract is available at http://onlinelibrary.wiley.com/doi/10.1002/cncr.27923/abstract.