Does obesity complicate cancer treatment?
Since 1975 worldwide obesity has tripled.
A 2016 report stated that more than 1.9 billion adults, 18 years and older, are overweight. Of the 1.9 billion, 650 million were reported to be obese.
The link between obesity & an increase in cancer risk has been observed. In fact, 1 in 20 cancer cases in the UK is caused by excess weight.
It is beneficial to note that a healthy weight reduces the risk of about 13 different types of cancer.
In India, about 135 million+ individuals are affected by obesity. And with the advent of socio-economic development in the country, a part of the urban Indian population falls in the category, putting them at a higher risk of being diagnosed with cancer.
Correlation between obesity and cancer
A multitude of researchers has shown through extensive research that excess body fat increases the risk of several cancers including colorectal cancer, postmenopausal breast cancer, uterine cancer, esophageal cancer, kidney cancer, and pancreatic cancers.
According to experts, obesity-related cancer can be due to inflammation caused by visceral fat. Visceral fat has large cells, and they are many in the body protecting vital organs. An obese individual has more visceral fat in their body, leaving less room for oxygen. This low oxygen triggers inflammation. Not only that, but excess fat also affects different body processes, including how certain hormones like insulin and estrogen are managed.
All of this can increase the risk of cancer by indirectly affecting how cells divide & how they die.
Changes in the populations of immune cells due to diet, & in turn, obesity is also known to increase the risk of cancer. Obesity can reshape cancer cell mechanisms impairing T-cells’ inflammatory functions. It remodels cellular fuel use of tumors, increasing the fatty acid oxidation of cancer cells & reducing the numbers as well as the spatial positioning of CD8+ cells. This, in turn, reduces antitumor immunity.
Obesity and cancer treatment
Top cancer doctors and oncology researchers vouch for the fact that lean cancer patients mostly outlive obese cancer patients. Previously, it was believed to be only because of obesity itself. But today, cancer specialists are realizing that bad outcomes can be tied to mistreatment based on individual requirements. You see, obese patients come with risks that others do not, and that warrants a different treatment approach.
In this blog, we will discuss the effect of obesity on different cancer treatments.
- Cancer Surgery
The correlation between obesity & cancer surgery is a mixed bag. In the case of breast, colorectal, and intra-abdominal cancer, no correlation between BMI & short-term or long-term mortality along with major surgical complications has been found. But there is an increased frequency of minor surgical complications, which might increase costs, reduce the quality of life, & delay adjuvant therapy. Studies on prostate cancer, on the other hand, demonstrated prolonged surgical time & greater blood loss in obese patients. The effect of obesity was also correlated with an increased chance of recurrence, poor outcome, and potential need for different adjuvant treatments.
- Radiation Therapy
Among prostate cancer patients being administered external beam radiation therapy, inferior outcomes due to obesity have been noted. External problems may arise as well; for example, delivering issues, like difficulty with daily set & increased likelihood of cancer location shifting. Not only that but it has also been observed that obese cervical cancer patients can even experience an increased rate of treatment-related toxicity compared to patients in the normal weight range. In breast cancer patients, cancer doctors have seen that a larger breast size & higher BMI can be associated with a higher risk of cute or late dermatitis after radiation.
- Chemotherapy
The dosing of chemotherapy drugs, which is essential in treating cancer, is calculated using BSA or body surface area in adults. Chemotherapy dosing is extremely important in treating cancer because it decides efficacy. Unfortunately, up to 40% of obese patients receive limited chemotherapy dosing, which does not correlate to their actual body weight. Why? Because of toxicity concerns among obese patients due to the higher dose of medication based on their actual body weight.
Also, obese cancer patients often have comorbidities like vascular disease or diabetes. This increases the chances of peripheral neuropathy. Baseline peripheral neuropathy is often associated with dose-limiting chemotherapy‐induced neurotoxicity.
But a low dose of chemotherapy can increase chances of disease recurrence and mortality, contributing to low survival rates.
- Hormonal Therapy
Endocrine therapy is a common adjuvant treatment for hormone-receptor-positive breast cancers with appropriate hormone receptors. In patients using tamoxifen, no correlation was found with obesity and efficacy or recurrence. But in premenopausal women taking ovarian suppression medication, high BMI was associated with low efficacy of endocrine therapies inhibiting aromatase and promoting the production of estrogen, including from adipose tissue, like anastrozole and goserelin. Aromatase Inhibitors or AI did not give as good results in obese women as they did in leaner women.
- Immunotherapy & stem cell therapy
There is very little information available regarding the efficacy of immunotherapy or stem cell therapy among cancer patients concerning BMI, whether normal or higher.
Does obesity hamper cancer treatment – Conclusion
Further research is needed to get a clearer picture of the correlation between the efficacy of cancer treatment and obesity because there are multiple gaps in the literature. While most research associated BMI with obesity, BMI cannot measure the adiposity of a body, which is important for treatment efficacy. Hence, more research is required in the area. However, the studies conducted so far have given a clear indication that obesity negatively impacts several cancer treatments, the bounds of which we are still discovering.
Note
Dr. Manish Singhal is a leading cancer specialist in Delhi NCR. With an acute understanding of lifestyle choices affecting cancer & cancer treatment, he & his team have successfully created efficient and customized cancer treatment plans for patients suffering from obesity and its many associated issues.
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