The results from this randomized trial examining the effect of moderate physical activity as prehabilitation in women undergoing breast cancer surgery did not show effects on QoL at 4 weeks or 12 months after surgery. Previous studies on QoL during adjuvant treatment [15] have primarily investigated effects following supervised, high intensity exercise interventions for a longer period of time [11]. Even with such intense exercise interventions, significant improvements in quality of life have not been reported [11]. This may in part be explained by a high baseline level of QoL in breast cancer patients, as also seen in our trial, and difficulties to detect and/or discriminate improvements from this level. The aim of our trial was to investigate the effect of a simple non-supervised intervention, in keeping with national and international recommendations regarding physical activity [25]. The intervention was chosen, assumed to be easily implementable and with slight impact on the care pathway for breast cancer treatment.
The FACT-G score in our trial cohort revealed a higher level of QoL, with a mean baseline score of 86, compared to 77 in the normative data for the general Swedish female population sample (pro-rated mean FACT-GP scores) [26]. The FACT-G minimally important difference (MID) is considered to be approximately 5–6 in a breast cancer population, with a MID 7–8 for the total FACT-B score [27]. The higher FACT-G score in our sample of breast cancer patients could suggest a selection bias, where individuals with lower QoL declined participation. Another possible explanation is the difference in age distribution in our study sample (mean 62 years) compared to the population sample (mean 49 years), as a higher age was positively correlated to higher FACT-GP score. Moreover, the FACT-G and FACT-B scores we present are similar to previously published results for breast cancer patients [28–30]. Over time, the FACT-B scores were stable regardless of study group and treatment factors, except for the subgroup of patient receiving adjuvant chemotherapy, where a significant decline was seen. Interestingly, this was not only seen at 12 months but also at 4 weeks, when the participants had not yet started their adjuvant chemotherapy but had gained information about the projected start of treatment.
EQ-VAS median score was stable regardless of study group and time for assessment and all changes seen in mean scores were less than the MID of 8 for EQ-VAS [31]. RAND-36 showed a temporary decline in the domains “Pain” and “Role limitations due to physical health” at 4 weeks, these changes were not seen at 12 months where participants had resumed their QoL. Interestingly, the domain “Emotional well-being” showed even better results at 12 months compared to baseline, possibly as a result of improved adaptive strategies and response shift over time. The domain “General health” improved during the active intervention period at 4 weeks after surgery, but at 12 months returned to baseline.
The consistency in FACT-B and EQ-VAS score from baseline to 4 weeks after surgery could indicate an inability of the instruments to encompass or discriminate changes resulting from the surgical insult, or that breast cancer diagnosis and surgery alone in fact has low impact on QoL. A significant difference was only seen for patients receiving adjuvant chemotherapy, compared to patients not receiving adjuvant chemotherapy, suggesting that this is a subgroup of patients that may benefit more from interventions aimed at improving QoL.
The strengths of the current study include the randomized controlled design, the use of several validated QoL instruments, both generic and disease specific, as well as both short- and long-term follow-up. Limitations include the lack of objective measures of physical activity, regarding type, duration and/or intensity of physical activity. Low adherence to the intervention, confine the effects of this non-supervised intervention and point to the draw-backs of recommendations regarding exercise, in line with previous studies [11, 32]. Our results, in accordance with previous findings seem to suggest the need for improved strategies and additional support in order to achieve the recommended physical activity level for patients with breast cancer.