Weighing in after breast cancer

Breast cancer remains the most common cancer in women in Australia, and by 2040 we expect to diagnose 25,000 new cases annually. With survival rates high, GPs are likely to care for many women who have experienced breast cancer.
 
Surviving cancer comes with a raft of continuing challenges, ranging from coping with symptoms of treatment (such as hot flushes or lymphedema) to fear of recurrence.
 
But GPs also need to be aware of a lesser known concern for survivors – weight gain.
 
Women commonly gain weight after being diagnosed with and treated for breast cancer. This may have implications on risk of disease recurrence and mortality, as well as a negative impact on quality of life.
 
Weight gain after breast cancer diagnosis is thought to be multifactorial and may be related to the use of systemic treatment, younger age at diagnosis, and changes in lifestyle.
 
Research my team at Western Sydney and Macquarie universities conducted on Australian women with breast cancer indicates that the proportion of those who are overweight or obese rose from 48% at diagnosis to 67% after diagnosis. What is a particular concern is the fact that our study – currently under review – found a doubling of the proportion of women with obesity.
 
The women in our study were mostly Caucasian with an average age of 59.1 years. Of these, 254 had stage I-III breast cancer and 33 had ductal carcinoma in situ (DCIS).
 
The majority of women (64%) reported they had gained weight after diagnosis, with an average gain of just over 9 kg in this group.
 
Half of all women surveyed gained 5 kg or more, while 17% gained more than 20 kg. Over half – 61% – experienced an increase in BMI of over 1 kg/m².
 
More than half of these survivors rated concern about their weight as ‘high’.
 
So what do breast cancer survivors do if concerned about associated weight gain?
 
About two-fifths of the women in the study had tried some kind of diet in the previous 12 months. However, there were challenges associated with treatment, with 38% reporting they were less active than they were at the time of diagnosis, and 42% doing either no exercise or low levels of physical activity.
 
The most commonly cited enabler of weight loss was a structured exercise regimen. Other facilitators included following a prescribed diet, being accountable to someone else and informal social support.
 
Lack of willpower and motivation was cited as the as the number one barrier to weight management, followed by fatigue and side effects from treatment.
 
Unsurprisingly, women who cited fatigue as a barrier were more likely to report low levels of physical activity.
 
These findings are of concern because weight gain before and after breast cancer diagnosis is both associated with increased morbidity and mortality.
 
For example, an observational study found each 5 kg gain in weight post-diagnosis to be associated with a 12% increase in all-cause mortality, 13% increase in breast cancer-specific mortality, and 19% increase in cardiovascular-disease mortality, after an average 6.3 years’ follow-up.
 
Coupled with the findings from my team’s study, this indicates that around half of women with breast cancer will face an increased risk of recurrence and mortality due to weight gain of over 5 kg.
 
In addition, weight gain can exacerbate the considerable body image concerns already faced by breast cancer survivors, has a negative impact on quality of life, and may be a cause of distress if it was unanticipated.
 
GPs are well placed to decrease the health burden due to weight gain after breast cancer because we provide comprehensive, whole-person care.
 
In consultations with patients with breast cancer, GPs could consider:  

• discussing the potential for weight gain after breast cancer, particularly in women who have had systemic treatment, or who are younger or premenopausal at the time of cancer diagnosis. This conversation needs to happen early, ideally within 6–12 months after diagnosis, as our research and the wider literature indicate that weight gain happens within that first year
• promote physical activity as a means to improving many aspects of health, wellbeing and survivorship. The Clinical Oncological Society of Australia last year strongly advocated for exercise to be embedded as part of standard practice in cancer care
• referring patients early to an experienced multidisciplinary team, including an accredited exercise physiologist and dietitian experienced in cancer. Literature tells us that the combination of diet, physical activity and behaviour modification is more effective than single interventions alone, while behaviour modification would also help to address the issue around lack of willpower
• pay particular attention to women with fatigue, since many have cited this as a barrier to being active, yet physical activity – particularly when supervised – is actually an effective treatment for post-cancer fatigue
• consider referring patients with fatigue to an exercise physiologist experienced in cancer. Cognitive and behavioural strategies, as well as mindfulness and yoga-based interventions also show promise in alleviating post-breast cancer fatigue
• monitor for and manage cardiovascular risk factors if women have gained weight.

breast cancer exercise obesity weight gain