This prospective study suggests that an evidence-based tailored educational nutritional intervention during treatment for EBC can increase the adherence to dietary guidelines and improve the anthropometric measures and the serum metabolic biomarkers in patients with high adherence. Unlike other cancers, weight gain after EBC diagnosis represents a common and relevant issue, as reported by a series of observational studies, considering that women who are overweight or gain weight after diagnosis seem to be at greater risk for breast cancer recurrence and death compared with lighter women . In these studies, the weight gain, considered clinically relevant when it is more than 5% of pre-diagnosis weight, was assessed in the first years after diagnosis or after the completion of adjuvant treatments . Conversely, in our analysis, almost half of the patients already gained more than 5% of their usual weight before starting neoadjuvant/adjuvant chemotherapy or adjuvant hormonotherapy. Moreover, this weight gain needs to be examined within the context that, at diagnosis, many patients in our study were overweight (38.2%), obese (23.9%), and central obese (52.7%). Concerning menopausal status at diagnosis, we did not detect any difference in the extent of weight increase between premenopausal and postmenopausal patients, while we reported more central obesity in postmenopausal women, strengthening the hypothesis that the excess of adiposity may be a breast cancer risk factor only for postmenopausal women . The weight gain in EBC may be related and influenced by a combination of phycological factors and behavior . In this context, we observed a significant correlation between both baseline BMI and weight gain with tension, worry, irritability, and depression, as well as with the levels of physical activity, measured by IPAQ. In line with previous evidence , many women of our cohort (79%) were inactive. A significant decline in levels of physical activity is very frequent after EBC diagnosis, leading to change in body composition, as well as compromise physiological and psychological functions, potentially worsening breast cancer outcomes [25, 26]. Besides, a change in the role of food, in eating behavior and nutrition status is common among women after diagnosis. Indeed, our cohort presented a high-fat dietary pattern, exceeding the 20% of total energy, as recommended by current evidence [12, 27], and a low fiber intake, which were both found to have independent effects on serum estrogen levels [28, 29]. Although some women tend to opt for a healthier diet after diagnosis, there are reports that they find comfort in consuming less healthy foods, using them as a reward for the difficult period of therapy . With regard to food consumption, we observed a low consumption of fruits, vegetables, and legumes and increased intake of high energy-dense and nutritionally poor foods, in line with previous findings .
Promising evidence suggested that weight gain may be prevented in EBC patients with diet intervention, achieving weight maintenance or loss [32, 33]. The educational component of our intervention was based on international recommendations, promoting the Med-Diet, not using group educational sessions . Patients may be more comfortable with a program that can address their specific needs and concerns, as well as reinforce the survivor-specific benefits of improved lifestyle factors. Moreover, the scheduled visits were by face-to-face contact during treatment and not by mail or telephone recall, as reported in several studies [35, 36], ensuring a more active role of the patients in dietary change and, thus, determining probably better adherence to dietary guidelines.
The Med-Diet has been shown to support weight loss and improve the inflammatory profile in cardiac and diabetic groups . Given the tendency for EBC patients to gain body weight and risk for metabolic syndrome, the Med-Diet may have a crucial role, promoting weight loss and offering multiple benefits due to fiber and antioxidants content. . Several studies investigated the relationship between dietary interventions and weight management in EBC survivors, providing support for the efficacy for achievement weight loss . However, a small number of nutritional interventional analyses focused on a Mediterranean-like dietary pattern [39-41].
After the 12-months evidence-based tailored nutritional intervention, dietary habits were changed, improving in plant food intake, and the adherence to dietary guidelines significantly increased compared to baseline. Consist with these data, a recent randomized trial, including 153 overweight and obese EBC survivors, reported that patients who received a dietary intervention significantly increased adherence to Med-Diet guidelines compared to patients who received informational brochures (+22.5% vs. +2.7%, p<0.001) . In our study, a high adherence, achieved by 62.6% of patients, significantly impacted weight loss, leading to a median BMI and WC drop. Particularly, high adherence Med-Diet resulted as a significant predictive factor in the multivariate analysis for BMI change. The proportion of overweight and obese patients considerably declined (from 39.5% to 13.8 and from 9.2% to 3.3%, respectively, p=0.003) and there was a significant reduction of patients with central obesity (from 38.2% to 7.2%, p=0.01). Furthermore, after the dietary intervention, none of the patients were found underweight. This represents a relevant aspect since that a series of observational studies reported an association between low BMI and increased risk of local recurrence and death [43, 44]. . Focus on the anthropometric measures’ change, Finocchiaro et al. evaluated 100 women previously treated for EBC submitted to an individualized intervention program based on WCRF/AICR guidelines and modeled on Med-Diet. They observed a significant improvement of adherence to the Med-Diet, with a statistically significant decrease in mean BMI and WC. However, this analysis recruited patients when they completed any chemotherapy treatment , thus when most of the weight gain has already occurred.
Concerning the serum metabolic biomarkers, in our study, patients with high adherence to dietary guidelines after the educational intervention reported an improvement in fasting levels of blood glucose and lipid profile, providing insight into the biological mechanisms through nutritional profile may impact on EBC outcome, reduce comorbidities and improve overall health. Indeed, both neoadjuvant and adjuvant treatments appear to determine a significant increase of blood glucose levels and worsening of lipid profile [10, 45]. These alterations, regardless of the speciﬁc cause, may persist up to 24 months after diagnosis and may be responsible for the worse prognosis in these patients . On the other hand, focusing on patients with low adherence to dietary guidelines, no BMI, WC, and blood tests’ differences were observed. Thus, our data emphasized the relevance of adherence to dietary guidelines in improving body weight and serum metabolic biomarkers. Considering that weight gain and altered metabolic profile after diagnosis has been frequently reported for EBC patients, especially among women receiving systemic chemotherapy , these data confirm the efficacy of dietary counselling by a registered dietitian in preventing weight and metabolic negative changes. Of note, overall, after the educational intervention, the WC reduction was correlated with an enhancement of emotional function, confirming previous evidence suggesting that improving weight-related distress plays an important role in increasing the well-being of EBC patients .
A limit of this study is represented by the fact that the body composition was evaluated by the WC (a surrogate measure of the visceral fat area), without the lean tissue mass assessment leading to potentially missed diagnoses of sarcopenic obesity . Besides, the effect of the dietary intervention on the EBC recurrence and survival is not evaluated, due to the short median follow-up. However, available evidence suggests the prognostic impact of nutritional intervention [12, 19]. In this regard, several trials evaluating the impact of weight loss and other lifestyle changes after breast cancer diagnosis on recurrence risk and mortality are currently ongoing [50, 51]. Nonetheless, the present study presents several strengths, including an accurate evaluation of anthropometric measures and dietary intake detected by trained dietitians, not based on patient’s self-reporting. Likewise, the nutritional intervention was customized on an individual basis, with regular visits directly with the patient and not by mail or telephone recall. Notably, we recruited women before starting the systemic therapy and we included patients regardless of their baseline BMI, evaluating the effect of the dietary intervention on body weight also in underweight patients.