The Society for Human Nutrition

Breast cancer: the right diet is also important for treatment

55 per cent of women with breast cancer are overweight or obese. The Italian Society of Human Nutrition is at the forefront of efforts to promote wider adoption of guidelines on weight management and the promotion of physical activity

by Francesca Indraccolo

8 July 2026

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4' min read

Translated by AI

Versione italiana

Key points

The prognosis may be affected by being overweight
A condition that can take its toll on both body and mind
The role of weight and body fat distribution
Metabolic profiling as a predictive tool
Taking a proactive approach to provide the best possible care for patients
The importance of diet and physical activity

4' min read

Translated by AI

Versione italiana

In modern oncology, nutrition is no longer merely a matter of common-sense advice, but has become a clinical pillar of the treatment pathway, on a par with surgery, radiotherapy or chemotherapy. Integrating nutritional support into treatment protocols and follow-up care means taking concrete action to improve patients’ ability to tolerate treatments, preserve their quality of life and, ultimately, positively influence overall survival. This topic, with a particular focus on women with breast cancer, was addressed by the Italian Society of Human Nutrition (SINU) during its 46th National Congress held in Bergamo, with a view to promoting wider dissemination of the relevant guidelines.

In women with breast cancer, who may be more susceptible to cardiometabolic complications than those with other cancers, overnutrition is increasingly being observed, often accompanied by sarcopenic obesity and metabolic abnormalities.

Prognosis may be affected by being overweight

“Patients,” explains Alessio Filippone, deputy coordinator of the SINU working group on “Nutrition in Oncology” and a member of the Integrated Breast Cancer Therapies team at the Fondazione Policlinico Gemelli – experience profound changes in their body composition due to systemic treatments, hormonal therapies and iatrogenic menopause; these factors, combined with a reduction in physical activity following diagnosis, lead to an increase in visceral fat at the expense of muscle mass. This scenario, which is less obvious but equally significant in prognostic terms, calls for a paradigm shift, with clinical strategies aimed at rebalancing body composition and the metabolic profile”.

A condition that can take its toll on both body and mind

Breast cancer is the most common cancer among women worldwide. According to GLOBOCAN estimates, there were 2.3 million new cases in 2022, accounting for 24 per cent of all new cancer cases in women. In Italia, according to AIOM estimates for 2025, more than 50,000 women are diagnosed with breast cancer each year, with a five-year survival rate of 88% and a prevalence of 925,000 survivors of the disease.

A diagnosis of breast cancer can cause physical and mental distress and bring about significant changes to daily life, including fatigue and pain resulting from the disease, surgery and adjuvant cancer treatment. Added to all this is the problem of weight gain.

The role of weight and body fat distribution

At the Breast Unit of the Policlinico Gemelli – a leading centre for central and southern Italia, where 1,500 new breast cancer patients undergo surgery each year – an integrated care pathway was introduced around 12 years ago, which involves assessing metabolic status from the very early stages of treatment. The nutritional pathway forms part of the multidisciplinary model of the Breast Centre at the A. Gemelli IRCCS, headed by Professor Gianluca Franceschini, and is delivered within the Integrated Therapies Clinical Unit, led by Dr Stefano Magno, as part of a personalised and multidisciplinary approach to patient care.

Metabolic profiling as a predictive tool

“55 per cent of women with breast cancer,” adds Filippone, “are overweight or obese and, as a result of excessive body fat, are at greater risk of haematological and neurological toxicity from treatment. Furthermore, body weight is a factor that can have a significant impact on prognosis. The most recent epidemiological evidence indicates that excess body fat is associated with an increased risk of mortality,” emphasises Filippone.

One key finding to emerge from the literature is that it is not just total body weight that matters, but also the distribution of body fat. “Abdominal adiposity is associated with a poorer prognosis and is linked to specific metabolic changes that may promote tumour progression,” adds Filippone.

Taking a proactive approach to provide the best possible care for patients

According to the main national and international guidelines – including the AIOM 2024 guidelines, ESPEN 2021 and the recent WCRF/AICR 2025 recommendations on dietary patterns – early nutritional screening in cases of breast cancer is crucial: identifying metabolic risk at the time of diagnosis allows intervention before functional decline becomes irreversible. “This is the approach taken by the Policlinico Gemelli’s care pathway, and we are also working to roll out this model so that it can become a right for all patients,” notes Filippone.

As regards clinical guidelines, nutritional support should aim to maintain an adequate protein intake, in order to support the immune system and preserve muscle mass. “At the same time, it is essential to manage blood sugar levels; therefore, the diet should prioritise complex carbohydrates and reduce simple sugars and alcoholic drinks, the latter being directly linked to an increased risk of relapse,” emphasises Filippone.

The importance of diet and physical activity

The Mediterranean diet plays a key role, being associated with a 22 per cent reduction in all-cause mortality and a significant decrease in recurrence. Furthermore, the cardiovascular benefits of this dietary pattern are particularly significant in women with a history of breast cancer, for whom cardiovascular risk becomes the leading cause of death several years after diagnosis.

Alongside nutrition, physical activity is a cornerstone of cancer care. “Well-established evidence suggests that regular exercise following diagnosis can reduce overall mortality by up to 44 per cent and the risk of recurrence by 35 per cent. Even moderate levels of exercise contribute to improving body composition, reducing visceral fat and restoring muscle mass. In addition to the biological effects, physical activity significantly improves quality of life by reducing fatigue, anxiety and depression,” explains Filippone.

According to the SINU survey carried out in Italian Breast Units, only 34 per cent of them have structured and standardised nutritional pathways. To bridge this gap and strengthen the integration between nutrition, prevention and cancer treatment, the SINU working group ‘Nutrition in Oncology’ is developing nutritional guidelines for breast cancer patients, taking into account lifestyle, the maintenance of a healthy weight, a balanced diet and a level of physical activity compatible with their clinical condition.