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Different metabolic factors may be linked to breast cancer recurrence and survival, Norwegian researchers Lofterød and colleagues find in a new study.
Breast cancer is the most common kind of cancer in women and results in hundreds of thousands of deaths each year. Improvements in identifying different kinds of breast cancer have helped improve treatment and survival of breast cancer patients. Although obesity and other metabolic factors are linked to the incidence of breast cancer generally, researchers do not yet understand how metabolic factors, such as levels of HDL cholesterol and triglycerides, affect different kinds of breast cancer and breast cancer recurrence. Understanding these relationships is important for treating breast cancer patients in the long term.
In a new study published in BMC Cancer, Trygve Lofterød and colleagues investigated the relationship of metabolic factors to different kinds of cancer. They followed 464 Norwegian women with verified invasive breast cancer diagnoses. The patients’ data were available from a large study on chronic disease carried out between 1979 and 2008. They analyzed blood samples for total cholesterol, HDL cholesterol, and triglycerides, and analyzed tumor samples to determine tumor characteristics. They also tracked survival after cancer treatment.
Of the women in the study, 129 died during the study follow-up period. Just over half of these deaths could be attributed to breast cancer. The most common type of breast cancer was Luminal A, which was linked to better survival and smaller tumors.
Triglycerides, total cholesterol, and HDL cholesterol were not linked to overall mortality or to Luminal A or B cancer types. Among patients with triple-negative breast cancer, those with high triglycerides had on average three times the mortality risk and 20% lower survival than patients with low triglycerides. However, patients with this kind of breast cancer and high HDL cholesterol had a 67% lower mortality risk. Among patients with HER2-positive breast cancer, those with high triglycerides had 86% reduced mortality risk compared to those with low triglycerides.
HDL cholesterol is linked to aggressive tumors, and is also linked to tumor-promoting inflammatory cells. However, HDL cholesterol may also act against tumors by preventing the growth of blood vessels in these tumors. Triglycerides, on the other hand, may correlate with constant low-level inflammation, which itself is linked to cancer severity.
Further work is needed to address why different types of breast cancer show different relationships to metabolic characteristics of patients. Understanding these mechanisms will improve patient survival and prognosis, and will help predict breast cancer recurrence.
Written by C.I. Villamil
Reference: Lofterod et al. 2018. Impact of pre-diagnostic triglycerides and HDL-cholesterol on breast cancer recurrence and survival by breast cancer subtypes. BMC Cancer 18:654.