Here is why you should lose weight if you were overweight or obese before diagnosis, or if you gained weight during breast cancer treatment:

a) Obesity decreases breast cancer treatment efficacy:

1. Triple negative patients without positive lymph nodes have a worst prognosis than normal weight patients.  – Bonsang-Kitzis si colab., 2015
2. Obesity decreases ER+/PR±/HER2+ breast cancer survival by diminishing Tamoxifen and Herceptin treatments efficacy. – Pande et al., 2014
3. Overweight and obese non-metastatic breast cancer patients have a lower response to neoadjuvant chemotherapy – Litton et al., 2008
4. Weight gain during chemotherapy increases the risks of recurrence and mortality – Thivat, 2010
5. The antiestrogenic treatment with aromatase inhibitors (Letrozole, Anastrozole or Exemestane) has less efficacy in postmenopausal obese breast cancer patients – Ioannides et al. 2014

b) Obesity increases the incidence and amplitude of breast cancer treatment side effects:

1. Obesity increases the risk of risk of persistent pain after breast cancer surgery. – Ding et al., 2017
2. Obesity is associated with a nearly 12-fold increased odds of a postoperative complication after elective breast procedures. – Chen et al., 2011
3. Obesity increases breast cancer secondary lymphedema risk. – DiSipio et al., 2013
4. Obesity increases radiotherapy skin toxicity. – Kraus-Tiefenbacher et al., 2012
5. Obesity associates an increased risk of depression – Ishii et al., 2016
6. Increased adiposity decreases vitamin D bioavailability – Parikh et al., 2004

c) Breast cancer patients obesity increases the risk of metastasis:

1. Obesity increases metastasis risk and decreases survival in  ER-/PR±/HER2+ breast cancer patients – Mazarella et al., 2013
2. Obesity increases the risk of lung and liver metastasis, and chemotherapy is less efficient in obese breast cancer patients – Osman and Hennessy, 2014
3. Obesity increases metastasis risk – Strong et al., 2015; Dowling et al., 2016
4. Obesity increases lung metastatis risk – Nagahashi et al., 2016
5. Obesity increases metastasis risk and decreases survival in  ER-/PR±/HER2± breast cancer patients – Wu et al., 2017

d) Obesity decreases breast cancer patients overall survival:

1. Obesity is an indepenedent factor that increases the risks of metastasis and breast cancer specific mortality, adjuvant therapies efficacy being lower in obese and overweight breast cancer patients – Ewertz et al., 2010
2. Obesity decreases overall survival independently of lymph node positivity – Kaviani et al., 2013
3. Obesity and diabetes have a negative impact on breast cancer survival – Jiralerspong et al., 2013
4. Obesity is an independent factor risk that decreases overall survival in ER+/PR±/HER2- postmenopausal breast cancer patients with lymph node involvment – Arce-Salinas et al., 2014; Scholtz et al., 2015
5. Obesity decreases overall survival in ER+ breast cancer patients younger than 40 years of age – Copson et al., 2015
6. Obesity increases breast cancer patients risk of mortality  – Chan and Norat, 2015

References:

Arce-Salinas, C., et al. “Overweight and obesity as poor prognostic factors in locally advanced breast cancer patients.” Breast cancer research and treatment 146.1 (2014): 183-188.

Bonsang-Kitzis, Hélène, et al. “Beyond axillary lymph node metastasis, BMI and menopausal status are prognostic determinants for triple-negative breast cancer treated by neoadjuvant chemotherapy.” PloS one 10.12 (2015): e0144359.

Chan, Doris SM, and Teresa Norat. “Obesity and breast cancer: not only a risk factor of the disease.” Current treatment options in oncology 16.5 (2015): 1-17.

Chen, Catherine L., et al. “The impact of obesity on breast surgery complications.” Plastic and reconstructive surgery 128.5 (2011): 395e-402e.

Copson, E. R., et al. “Obesity and the outcome of young breast cancer patients in the UK: the POSH study.” Annals of Oncology 26.1 (2015): 101-112.

Ding, Yuan-Yuan, et al. “Body mass index and persistent pain after breast cancer surgery: findings from the women’s healthy eating and living study and a meta-analysis.” Oncotarget 8.26 (2017): 43332.

DiSipio, Tracey, et al. “Incidence of unilateral arm lymphoedema after breast cancer: a systematic review and meta-analysis.” The lancet oncology 14.6 (2013): 500-515.

Dowling, R. J. O., et al. “Abstract P2-02-09: Obesity associated factors are inversely associated with circulating tumor cells in metastatic breast cancer.” (2016): P2-02.

Ewertz, Marianne, et al. “Effect of obesity on prognosis after early-stage breast cancer.” Journal of Clinical Oncology 29.1 (2010): 25-31.

Ioannides, S. J., et al. “Effect of obesity on aromatase inhibitor efficacy in postmenopausal, hormone receptor-positive breast cancer: a systematic review.” Breast cancer research and treatment 147.2 (2014): 237-248.

Ishii, Shinya, et al. “The association between sarcopenic obesity and depressive symptoms in older Japanese adults.” PloS one 11.9 (2016): e0162898.

Kaviani, Ahmad, et al. “Effects of obesity on presentation of breast cancer, lymph node metastasis and patient survival: a retrospective review.” Asian Pac J Cancer Prev 14.4 (2013): 2225-9.

Kraus-Tiefenbacher, Uta, et al. “Factors of influence on acute skin toxicity of breast cancer patients treated with standard three-dimensional conformal radiotherapy (3D-CRT) after breast conserving surgery (BCS).” Radiation Oncology 7.1 (2012): 217.

Mazzarella, Luca, et al. “Obesity increases the incidence of distant metastases in oestrogen receptor-negative human epidermal growth factor receptor 2-positive breast cancer patients.” European Journal of Cancer 49.17 (2013): 3588-3597.

Nagahashi, M., et al. “Abstract P2-05-11: Sphingosine-1-phosphate signaling promotes metastatic niches and lung metastasis in obesity-related breast cancer.” (2016): P2-05.

Osman, Mohammed A., and Bryan T. Hennessy. “Obesity Correlation With Metastases Development and Response to First-Line Metastatic Chemotherapy in Breast Cancer.” Clinical Medicine Insights. Oncology 9 (2014): 105-112.

Parikh, Shamik J., et al. “The relationship between obesity and serum 1, 25-dihydroxy

Pande, Mala, et al. “Association between germline single nucleotide polymorphisms in the PI3K-AKT-mTOR pathway, obesity, and breast cancer disease-free survival.” Breast cancer research and treatment 147.2 (2014): 381-387.

Jiralerspong, S., et al. “Obesity, diabetes, and survival outcomes in a large cohort of early-stage breast cancer patients.” Annals of oncology (2013): mdt224.

Litton, Jennifer K., et al. “Relationship between obesity and pathologic response to neoadjuvant chemotherapy among women with operable breast cancer.” Journal of Clinical Oncology 26.25 (2008): 4072-4077.

Scholz, Christoph, et al. “Obesity as an independent risk factor for decreased survival in node-positive high-risk breast cancer.” Breast cancer research and treatment 151.3 (2015): 569-576.

Strong, Amy L., et al. “Leptin produced by obese adipose stromal/stem cells enhances proliferation and metastasis of estrogen receptor positive breast cancers.” Breast Cancer Research 17.1 (2015): 112.

Thivat, Emilie, et al. “Weight change during chemotherapy changes the prognosis in non metastatic breast cancer for the worse.” BMC cancer 10.1 (2010): 648.

Wu, Yong, et al. “Aberrant phosphorylation of SMAD4 Thr277-mediated USP9x-SMAD4 interaction by free fatty acids promotes breast cancer metastasis.” Cancer Research (2017): canres-2012.

Articolul Why should overweight and obese breast cancer patients lose weight? apare prima dată în Nutrition Services | Nutritionist Dr. Diana Artene.