Evaluating the Outcome of a Personalised Oncological Rehabilitation Program in Overweight and Obese Breast Cancer Patients on Adjuvant Anti-hormonal Treatment "I-Move"

Rationale:

Patients diagnosed with breast cancer generally have a fairly well prognosis with estimated average survival rates of 73% and five year survival rates of 89% in developed countries (1). However, women who are obese at the time of breast cancer diagnosis seem to be at risk for a worse breast cancer related and overall survival, as compared to their normal weight counterparts. In addition, weight gain after diagnosis might be negatively associated with prognosis. Possible mechanisms explaining this association include host-related, tumour-related and treatment-related factors (2).

Regular physical activity (PA) after a diagnosis of breast cancer can have various beneficial effects with respect to overall survival (3) as well as health-related quality of life (4). The Dutch PA guideline "Nederlandse Norm Gezond Bewegen (NNGB)" recommends to engage in moderate-intensity exercise (e.g. brisk walking) for at least 30 minutes a day, on at least 5 days a week (5). For people who are overweight (Body Mass Index ≥ 25 kg/m2) it is recommended to exercise at least 60 minutes at a moderate-intensity level, equal or more than 3 Metabolic Equivalent Task Hours (> 3 MET/h), on at least 5 days a week (6,7). However, only 61% of the general population, meets these guidelines (8) and among cancer patients this percentage is even less (9).

The recently published national guideline oncological rehabilitation provides exercise goals, for physical training based on the NNGB (5) as well as advice regarding nutrition and education on maintaining a healthy lifestyle. The guideline emphasises the importance of a tailored program, taking into account personal preferences and attitudes concerning physical exercise. Level of PA self-efficacy (beliefs in one's capabilities to successfully execute the required PA) is mentioned as an important predictor of compliance.

Weight gain is a common phenomenon among breast cancer patients receiving adjuvant chemotherapy (10) as well as receiving adjuvant anti-hormonal therapy (11). While sufficient physical activity and limitation of the amount of weight gain is important for all breast cancer patients, it surely is for overweight and obese patients. In the provinces of Groningen and Drenthe, the percentage of overweight women is significantly higher compared to the national average. In addition, in this area the average socio-economic status (SES), often associated with unhealthy lifestyle, overweight and not seeing the personal relevance of health recommendations, is lower than in the rest of the Netherlands. This leaves this group extra vulnerable for all kinds of health problems like diabetes mellitus, hypertension, increased risk of cardiovascular disease and decreased cancer related survival. However, it is also known to be a population that is very difficult to motivate to engage in more physical activity. Therefore, it is uncertain if the guideline oncological rehabilitation is sufficient enough to reach the NNGB goals. Oncological rehabilitation can render health gain in this patient population, as it can potentially limit weight gain, improve parameters of metabolic syndrome and improve health-related quality of life.