Why Maintaining a Healthy Weight in Cancer Matters

Weight Gain and Cancer


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 discussed in an earlier blog, there is proven research suggesting that obesity is not just a contributing factor for increased risk of various types of cancer, but it is also linked to a worse result and a greater risk of cancer recurrence in a particular proportion of people.


Data from several countries show that in the next 15 years, obesity will run faster than smoking as a big cause of preventable cancer cases.

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/

For patients who are obese, there is reliable data showing obesity is related 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 (especially men) had an increased risk of local repeating 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 issue since not all obese patients have these same risks, there is no doubt that being at and maintaining a healthy weight is important in your cancer journey and afterward as a survivor.


An unhealthy amount of weight can make treatment more challenging and the road to recovery longer.


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.

Cancer And Losing Weight

Problems related to diagnosis

Obese cancer patients face many challenges none more so than the embarrassment of physical exams which can be from lack of extra-large gowns, to perceived and/or real problems 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 change something obese patients up to 680 pounds on CT scanners but these weight lossscanners are not available everywhere.


Image quality is directly related to the depth of soft tissue penetration. The greater thickness of the tissue to penetrate through (below the skin fat ) means more image noise and increased interesting (old) objects 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 mistakes related to the measurement of biomarkers in blood samples due to hemodilution from larger plasma quantities.


Biomarkers include tumour 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 a 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 in obese patients


Chemotherapy dosing is generally based on body surface area and overweight or obese patients are often undertreated because there are random limits used to calculate chemotherapy dosing due to concerns of toxicity.


Overweight and obese patients may receive limited or reduced chemotherapy doses.


Data suggest that reductions in chemotherapy dose intensity is associated with increased rates of cancer recurrence and cancer connected death 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 blood-vessel related 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.


Why Maintaining a Healthy Weight in Cancer Matters

Radiation therapy in obese patients


In patients receiving radiation therapy, the larger the patient is, the more radiation is needed to reach the tumour.


More radiation means that healthy areas of the body are more exposed to it and unfortunately, this can lead to higher toxicity.


Radiation skin swelling which is a result of this toxicity often happens in places where excess skin folds over on itself as is common in obese patients.


Weight loss or gain during treatment


When most people think about the 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 cancer treatment or later.


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 it worse for obese patients.


Chemotherapy may directly or indirectly lead to weight loss or weight gain.


A few pounds gained or lost post-treatment is not potentially worrisome, however, significant weight loss or weight gain may affect your health and/or your ability to tolerate further treatments.


Unexplained weight loss can potentially slow down or postpone treatment.


Weight loss due to chemotherapy may be related to treatment side effects including muscle loss, appetite loss, diarrhoea, nausea, and dehydration.


This is especially true for individuals with cancers of the mouth, throat, stomach, or other parts of the head and neck.


The malignancy, as much as the treatment, alters the patient’s ability and willingness to eat.


Similarly, weight gain in cancer patients may be related to decreased activity while on chemotherapy.


Some medications actually increase the appetite resulting in weight gain.


Fluid retention (swelling or edema). Some chemotherapy weight gain is caused by fluid retention (swelling or edema) but this can be temporary and managed by other medications such as diuretics.


Some chemotherapy habits contain steroids which can cause weight gain by changing the body’s electrolyte and water balances, as well as its metabolism by increasing appetite, causing fluid retention and changing fat distribution.


Many people on steroids notice increased fat in the abdomen, face, and neck.


“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


It is important to let your cancer care team know if you have sudden weight loss or weight gain of more than 3-5 pounds in a week, unexplained shortness of breath, swollen ankles or feet, dizziness, or suddenly tight shoes, clothes, or rings.


Maintaining a healthy weight before, during, and after treatment


With two-thirds of the American population classified as overweight or obese, many newly diagnosed cancer patients who fall into those categories have to redefine what healthy eating and healthy weight means for them.


Recommendations about weight management are unique to each patient.


Generally, certain recommendations are made for patients watching weight loss and cancer treatment including increased lean protein in their diet since protein is needed for wound healing, tissue upkeep, and development.


Protein is needed by the body to maintain muscle mass; those who hold muscle mass have fewer bad effects and earlier recovery after cancer therapy.


Among postmenopausal women, losing even 5% of their body weight, or 10 pounds on average, may lead to a lower risk of breast cancer compared to those who don’t lose weight. Cancer research shows that women who lost 5% or more of their body weight also had a lower risk of endometrial cancer.


Weight loss is able to be done but needs consistent behavioural change 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 watching 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.


Nutrition supplements or balanced diet with plant-based foods being the mainstay can help in maintaining a good weight and help you grow and do well.


Starting an exercise program may seem overwhelming, however, participating in physical activity can actually improve your energy level.


As always, you must consult with your cancer care team before embarking on any exercise or diet plan.


Please see previous blogs on how exercise can help you deal with cancer side effects and improve your general health.


As you change from treatment to survivorship it is extremely important that a healthy weight and functional behaviour changes become your path to grow and do well.


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Reason to Hope

There is new research from Brigham and Women’s Hospital that indicates a Western-style diet that is rich in red and processed meat, sugar and refined grains/carbohydrates is tied to higher risk of colorectal cancer through the intestinal microbiota.  Gastroenterology, 2022;DOI:10.1053/j.gastro.2022.06.054