Excess weight not only slows down recovery from cancer therapy but also complicates treatment itself.
“You don’t have to see the whole staircase. Just take the first step.”
As we spoke about in the previous blog, there is increasing evidence that in a certain percentage of the population, obesity is not only a risk factor for developing cancer, it is also associated with a worse prognosis and an increased risk for recurrence for those that have cancer. Data from several countries indicates that in the next 15 years, obesity will overtake smoking as a leading cause of preventable cases of cancer.
Each year, about 120,000 cancer diagnoses are attributed to excess body weight, which results in 15% to 20% of cancer-related mortalities. https://ascopost.com/issues/may-25-2017/tackling-the-obesity-and-cancer-epidemic/
There is substantial data showing obesity associated with increased risk of treatment-related lymphedema in breast cancer survivors and urinary incontinence in prostate cancer survivors treated with radical prostatectomy. In a clinical trial of patients with stage II and stage III rectal cancer, those with a higher baseline BMI (particularly men) had an increased risk of local recurrent cancer. Death from multiple myeloma is 50% more likely for people who are morbidly obese compared to their non-obese counterparts. While there is certainly more to the story since not all obese patients have these same risks or outcomes, there is no doubt that being at and maintaining a healthy weight is important in your cancer journey and afterward as a survivor.
Obese cancer patients face numerous challenges none more so than the embarrassment of physical exams which can be from lack of extra-large gowns, to exam tables with limited weight bearing capacity to perceived and/or real difficulties in doing pap smears/pelvic exams or breast exams.
All of which result in poorer health care when compared to their non-obese counterparts. Obese patients have limited ability to receive effective diagnostic imaging such as ultrasound, CT, PET-CT or MRIs. Weight limitations on scanning machines have resulted in manufacturers building scanners that accommodate obese patients up to 680 pounds on CT scanners but these bariatric scanners are not available everywhere. Image quality is directly related to the depth of soft tissue penetration. The greater thickness of tissue to penetrate through (subcutaneous fat) means more image noise and increased errors in image representation which reduces image quality and increases radiation dose to the patient. For ultrasound, there is a direct relationship between depth of tissue and loss in ultrasound energy resulting in a poor quality image. Oncologists rely on scans to determine staging, treatment response as well as side effects of treatments. Poor image quality can significantly decrease the accuracy of image interpretation.
Apart from imaging, there can be inaccuracies related to measurement of biomarkers in blood samples due to hemodilution from larger plasma volumes. Biomarkers include tumor markers which when measured serially over a period of time help assess treatment response. When it comes to surgery in obese cancer patients, there is proven association between high BMI and an increased incidence of surgical complications such as wound dehiscence (wound reopening that creates a new wound) and infection.
Overweight and obese patients may receive limited or reduced chemotherapy doses.
Chemotherapy dosing is generally based on body surface area and overweight or obese patients are often undertreated because there are arbitrary limits used to calculate chemotherapy dosing due to concerns of toxicity. Data suggest that reductions in chemotherapy dose intensity is associated with increased rates of cancer recurrence and cancer-associated mortality and other studies confirm the safety and importance of full weight-based dosing which is standard of care unless there are complicating factors. Obese patients are more likely to have comorbidities like vascular disease and diabetes, which can increase their risk of peripheral neuropathy, a side effect of some types of chemotherapy making it a double whammy. Other side effects including fatigue, sexual dysfunction, cardiotoxicity are all compounded by obesity.
In patients receiving radiation, the larger the patient is, the more radiation is needed to reach the tumor. More radiation means that healthy areas of the body are more exposed to it and unfortunately, this can lead to higher toxicity. Radiation dermatitis which is a result of this toxicity often occurs in places where excess skin folds over on itself as is common in obese patients.
When most people think about side effects of cancer treatment, they think about weight loss as one of those side effects. In fact, quite often, many patients will gain weight during or after treatment. Weight gain is most common in patients receiving chemotherapy, but patients who receive surgery or hormone therapy can gain weight after a cancer diagnosis which makes is worse for obese patients.
“We need to better understand how to leverage the teachable moments from cancer diagnosis through survivorship to educate families about lifestyle factors that affect weight control.” - Melissa M. Hudson, MD
Weight loss is feasible but requires consistent behavioral modification including how you think and approach food and exercise, making your health a priority, asking for direct help from your cancer care team and self-monitoring so you don’t derail your efforts. Many people find it easier to lose weight if they have a structured program and support. It is never too late to improve your health. Even small reductions or changes to what you eat and drink can help you lose weight consistently over time. Starting an exercise program may seem overwhelming however, participating in physical activity can actually improve your energy level. Please see previous blogs on how exercise can help you deal with cancer side effects and improve your general health.
As you transition from treatment to survivorship it is essential that a healthy weight and functional behavior changes become your path to thrive.