Adjuvant chemotherapy may contribute to an increased risk for metabolic syndrome in patients with breast cancer

Neoadjuvant therapy increases the risk of metabolic disorders and osteosarcopenia in patients with early breast cancer

BACKGROUND

The purpose of this study is to evaluate the effects of neoadjuvant therapy on glucose and lipid metabolism, bone mineral density (BMD) and muscle, and to explore the relationship between metabolic disorders and changes in body composition, so as to provide better health management strategies for breast cancer survivors.

METHODS

The clinical data of 43 patients with breast cancer who received neoadjuvant therapy in Xuanwu Hospital from January 2020 to June 2021 were analyzed retrospectively. The biochemical results, including albumin, blood glucose, triglyceride and cholesterol, were collected before neoadjuvant therapy and before surgery. The pectoral muscle area, pectoral muscle density and cancellous bone mineral density of the 12th thoracic vertebra were also measured by chest CT.

RESULTS

After neoadjuvant therapy, fasting blood glucose, triglyceride and cholesterol were significantly increased, albumin was decreased. At the same time, pectoral muscle area, pectoral muscle density and T12 BMD were decreased. After treatment, BMD was positively correlated with pectoral muscle area, R2 = 0.319, P = 0.037, and BMD was also positively correlated with pectoral muscle density, R2 = 0.329, P = 0.031. Multivariate analysis showed that BMD and pectoral muscle density were correlated with menstrual status, and pectoral muscle area was correlated with body mass index before treatment, none of which was related to glucose and lipid metabolism.

CONCLUSION

Neoadjuvant therapy can cause glucose and lipid metabolism disorder, BMD decrease and muscle reduction. BMD was positively correlated with muscle area and density after treatment, suggesting that patients had an increased chance of developing osteosarcopenia.

Lipid Disturbances in Breast Cancer Patients during Chemotherapy

Breast cancer is the most common cancer in women. Cardiovascular diseases are common complications after chemotherapy due to the effect of the drug on lipid levels. This study aimed to explore the changes in lipid profiles in patients with breast cancer under chemotherapy.

METHODS

In this prospective study, 50 patients with breast cancer participated. Three biochemical-lipid hematological tests were performed: total cholesterol (TC), triglycerides (TGs), High-Density Lipoprotein (HDL-C), and Low-Density Lipoprotein (LDL-C) before initiation (pre-chemotherapy), at the start (first follow-up), and at the completion (second follow-up) of the first cycle of chemotherapy. Statistical significance was set at p < 0.05. Analyses were conducted using SPSS Statistical Software (version 22.0).

RESULTS

Mean TC values increased significantly at second follow-up. TGs values decreased significantly from first to second follow-up. HDL-C was significantly lower at first follow-up compared with pre-chemotherapy and was similar to the pre-chemotherapy levels at second follow-up. LDL-C values were significantly higher at second follow-up compared with pre-chemotherapy measurement. Significantly positive correlations of BMI with pre-chemotherapy LDL-C, first follow-up TC, first follow-up LDL-C, second follow-up TC, and second follow-up LDL-C were found.

CONCLUSIONS

There is a statistically significant increase in the levels of TC and LDL-C in breast cancer patients during chemotherapy. This study was not registered.

Lipoprotein(a) in patients with breast cancer after chemotherapy: exploring potential strategies for cardioprotection

Developments in neoadjuvant and adjuvant chemotherapy (CHT) have led to an increase in the number of breast cancer survivors. The determination of an appropriate follow-up for these patients is of increasing importance. Deaths due to cardiovascular disease (CVD) are an important part of mortality in patients with breast cancer.This review suggests that chemotherapeutic agents may influence lipoprotein(a) (Lp(a)) concentrations in breast cancer survivors after CHT based on many convincing evidence from epidemiologic and observational researches. Usually, the higher the Lp(a) concentration, the higher the median risk of developing CVD. However, more clinical trial results are needed in the future to provide clear evidence of a possible causal relationship. This review also discuss the existing and emerging therapies for lowering Lp(a) concentrations in the clinical setting. Hormone replacement therapy, statins, proprotein convertase subtilisin/kexin-type 9 (PCSK9) inhibitors, Antisense oligonucleotides, small interfering RNA, etc. may reduce circulating Lp(a) or decrease the incidence of CVD.

Insulin resistance and weight gain in women treated for early stage breast cancer

PURPOSE

Both weight gain and insulin resistance have been associated with poorer prognosis in women receiving adjuvant therapy for early stage breast cancer, however, interactions between weight gain and insulin resistance have not been explored longitudinally throughout the breast cancer treatment continuum.

METHODS

One hundred non-diabetic women with early stage breast cancer receiving adjuvant chemotherapy and /or hormonal therapy were enrolled in this prospective, observational study. Metrics of weight, body composition (BMI, waist/hip circumference ratio (WHR)), and cardiometabolic health (fasting insulin, glucose and triglycerides) were obtained prior to adjuvant therapy (baseline) and repeated 6, 12, and 24 months post-diagnosis. Insulin resistance was calculated using the Homeostatic Model Assessment of Insulin Resistance (HOMA-IR).

RESULTS

Complete data were available for 95 participants. Compared to baseline, body weight was significantly higher at the 12-month time-point (75.3 ± 15.7 vs. 76.2 ± 16.7, p = 0.03), however there was no difference in waist circumference (p = 0.96) or WHR (p = 0.52). HOMA-IR tended to increase 6 months after diagnosis (2.36 ± 2.17 vs. 2.70 ± 2.83, p = 0.06), largely driven by adverse responses in patients treated with chemotherapy (mean change + 0.53 (chemotherapy) vs - 0.64 (no chemotherapy), p = 0.005). Despite 12-month weight gain, the 6-month increase in HOMA-IR was fully abrogated 12 months after diagnosis.

CONCLUSION

Breast cancer patients experience small but significant weight gain in the year following diagnosis, and those who receive chemotherapy experience significant short-term metabolic impairments suggestive of insulin resistance. While the acute insulin resistance appears to attenuate over time, the long-term ramifications are unclear and may help explain weight gain in this population.

Metabolic syndrome and breast cancer survivors: a follow-up analysis after completion of chemotherapy

BACKGROUND

We previously reported that (neo)adjuvant chemotherapy adversely altered metabolic syndrome (MetS) components, body composition, and related biomarkers after a 12 to 18-week chemotherapy treatment course in women. Here, we sought to determine whether these measures worsened within 4-5 years post-chemotherapy among the same sample of early stage breast cancer survivors.

METHODS

Twenty-eight breast cancer survivors were reassessed within 4-5 years post-chemotherapy. Participants were tested for MetS, lipid profile (total cholesterol; TC, low-density lipoprotein cholesterol; LDL-C), glucose metabolism (insulin, homeostatic model- insulin resistance; HOMA-IR, glycosylated hemoglobin; HbA1c), inflammation (C-reactive protein; CRP) and body composition (body weight; BW, percent body fat; BF, fat mass; FM) during follow-up physical exams. A comparison of measurements between post-chemotherapy and follow-up periods was performed using repeated measures analysis of covariance.

RESULTS

Most study patients were Caucasian (44%) or Hispanic (30%) with a mean age of 48.2 years. Average time from completion of chemotherapy was 4.75 years. At follow-up, MetS components significantly increased (p < 0.01) compared with the post chemotherapy assessment. Additionally, BF, FM, lipids (TC, LDL), glucose metabolism (HOMA-IR, insulin, HbA1c), and inflammation (CRP) significantly increased (p < 0.01). Notably BW significantly increased; mean weight gain after chemotherapy was 6.1 kg and increased an additional 8.2% at follow-up (p < 0.01).

CONCLUSION

MetS components, body composition, and biomarkers continued to worsen within 4-5 years post-chemotherapy in breast cancer survivors. Energy balance interventions should target breast cancer patients to reduce the exacerbation of MetS.

Probiotics for the Treatment of Docetaxel-Related Weight Gain of Breast Cancer Patients-A Single-Center, Randomized, Double-Blind, and Placebo-Controlled Trial

Background: Docetaxel is an important chemotherapy-agent for breast cancer treatment. One of its side-effects is weight gain, which increases the all-cause mortality rate. Considering gut microbiota is one important factor for weight regulation, we hypothesized that probiotics could be potentially used to reduce the docetaxel-related weight gain in breast cancer patients. Methods: From 10/8/2018 to 10/17/2019, 100 breast cancer (Stage I-III) patients underwent four cycles of docetaxel-based chemotherapy were enrolled and randomly assigned to receive probiotics (Bifidobacterium longum, Lactobacillus acidophilus, and Enterococcus faecalis) or placebo (supplementary material of the probiotics capsule) treatment for 84 days with three capsules per time, twice/day. The primary outcome: the changes in body weight and body-fat percentage of the patients were measured by a designated physician using a fat analyzer, and the secondary outcomes: the fasting insulin, plasma glucose, and lipids were directly obtained from the Hospital Information System (HIS); The metabolites were measured using liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS); The fecal microbiome was analyzed using bacterial 16S ribosomal RNA (rRNA) gene sequence. All indicators were measured 1 day before the first cycle of docetaxel-based chemotherapy and 21 days after the last cycle of docetaxel-based chemotherapy. Results: Compared with the placebo group, the probiotic group showed significantly smaller changes in body weight (Mean [SD] 0.77 [2.58] vs. 2.70 [3.08], P = 0.03), body-fat percentage (Mean [SD] 0.04 [1.14] vs. 3.86 [11.09], P = 0.02), and low density lipoprotein (LDL) (Mean [SD]-0.05[0.68] vs. 0.39 [0.58], P = 0.002). Moreover, five of the 340 detected plasma metabolites showed significant differences between the two groups. The change of biliverdin dihydrochloride (B = -0.724, P = 0.02) was inverse correlated with weight gain. One strain of the phylum and three strains of the genus were detected to be significantly different between the two groups. Also, the changes of Bacteroides (B = -0.917, P < 0.001) and Anaerostipes (B = -0.894, P < 0.001) were inverse correlated with the change of LDL. Conclusions: Probiotics supplement during docetaxel-based chemotherapy for breast cancer treatment may help to reduce the increase in body weight, body-fat percentage, plasma LDL, and minimize the metabolic changes and gut dysbacteriosis. Clinical Trial Registration: http://www.chictr.org.cn/showproj.aspx?proj=24294, ChiCTR-INQ-17014181.

Metabolic Syndrome and Breast Cancer: Prevalence, Treatment Response, and Prognosis

Metabolic syndrome is a type of multifactorial metabolic disease with the presence of at least three factors: obesity, diabetes mellitus, low high-density lipoprotein, hypertriglyceridemia, and hypertension. Recent studies have shown that metabolic syndrome and its related components exert a significant impact on the initiation, progression, treatment response, and prognosis of breast cancer. Metabolic abnormalities not only increase the disease risk and aggravate tumor progression but also lead to unfavorable treatment responses and more treatment side effects. Moreover, biochemical reactions caused by the imbalance of these metabolic components affect both the host general state and organ-specific tumor microenvironment, resulting in increased rates of recurrence and mortality. Therefore, this review discusses the recent advances in the association of metabolic syndrome and breast cancer, providing potential novel therapeutic targets and intervention strategies to improve breast cancer outcome.

Effects of Chemotherapy on Serum Lipids in Chinese Postoperative Breast Cancer Patients

Purpose

Chemotherapy is a comprehensive therapy for breast cancer; nevertheless, its associated adverse effects are drawing increasing attention with the continuous improvement of the efficacy. The changes in serum lipids of breast cancer patients caused by chemotherapy have been reported by previous studies, whereby the former increase the incidence rate of cardiovascular disorders. However, the variations in the changes of serum lipids with different chemotherapy regimens have seldom been reported.

Methods

From January 2011 to December 2017, 1740 breast cancer patients treated with chemotherapy were recruited at the First Affiliated Hospital of Nanjing Medical University. The chemotherapy regimens included anthracycline-based, taxane-based, and anthracycline-plus-taxane-based regimens, dose-dense and standard-interval regimens. Lipid profiles that contained TG (triglyceride), TC (total cholesterol), HDL-C (high-density lipoprotein cholesterol), LDL-C (low-density lipoprotein cholesterol) and Lpa (lipoprotein a) levels were collected prior to the first, second and last cycles of chemotherapy. The changes of serum lipids with the same or different chemotherapy regimens were analyzed and compared.

Results

It was observed that the levels of TG, TC, LDL-C and Lpa increased significantly while that of HDL-C decreased after adjuvant chemotherapy in breast cancer patients (P<0.05). Besides, dose-dense regimens had more influence in TG and HDL-C and less influence in TC and LDL-C than standard-interval regimens. HDL-C was more sensitive to anthracycline-based regimens than taxane-based regimens. The level of TG with anthracycline-plus-taxane-based regimens was higher than that with only anthracycline-based or taxane-based regimens, and the level of HDL-C with anthracycline-plus-taxane-based regimen showed lower than that with taxane-based regimen.

Conclusion

In summary, this study proposed that dyslipidemia was strongly associated with chemotherapy in Chinese breast cancer patients after operative treatment. Furthermore, the changes in levels of serum lipids varied among patients with different chemotherapy regimens and taxane had less effect on dyslipidemia than anthracycline.

Adjuvant chemotherapy-associated lipid changes in breast cancer patients: A real-word retrospective analysis

Adjuvant chemotherapy may cause alterations in serum lipids in postoperative breast cancer (BC) patients, but the specific alterations caused by different chemotherapy regimens remain unclear. The aim of this study was to investigate the status of serum lipids pre- and post-chemotherapy and to compare the side effects of different chemotherapy regimens on serum lipid.We retrospectively analysed the lipid profiles of 1934 consecutive postoperative BC patients who received one of the following chemotherapy regimens:The levels of triglycerides (TG), total cholesterols (TC), and low-density lipoprotein (LDL-C) were significantly elevated in patients who received chemotherapy regimens above (P < .001). With respect to different chemotherapy regimens, FEC had less side effects on lipid profiles (TG (P = .006), high-density lipoprotein (HDL-C) (P < .001), and LDL-C (P < .001)) than TC regimen and AC-T and EC-T regimen. Also, the incidence of newly diagnosed dyslipidemia after chemotherapy was lower in FEC group than TC group and AC-T and EC-T group (P < .001). Additionally, the magnitude of the alterations in lipid profiles (TG, TC, HDL-C, and LDL-C) was greater in premenopausal patients than that of the postmenopausal patients (P = .004; P < .001; P = .002; P = .003, respectively). Moreover, after adjusting for multiple baseline covariates, anthracycline-plus-taxane-based regimens (AC-T and EC-T) were still statistically associated with a high level of TG (P = .004) and a low level of HDL-C (P = .033) after chemotherapy compared with FEC regimen. Also, body mass index (BMI) > 24 was associated with abnormal lipid profiles (TG, TC, HDL-C, LDL-C) post-chemotherapy compared with BMI ≤ 24 (P < .001; P = .036; P = .012; P = .048, respectively).BC patients receiving chemotherapy may have elevated lipid profiles, and anthracycline-based regimen had less side effects on lipid profiles compared with regimens containing taxane. Therefore, it is necessary to take lipid metabolism into consideration when making chemotherapy decisions and dyslipidemia prevention and corresponding interventions are indispensable during the whole chemotherapy period.

The role of metabolic diseases in cardiotoxicity associated with cancer therapy: What we know, what we would know

Metabolic diseases, such as obesity and type 2 diabetes, are known risk factors for cardiovascular (CV) diseases. Thus, patients with those comorbidities could be at increased risk of experiencing cardiotoxicity related to treatment with Anthracyclines and the other new generation targeted anticancer drugs. However, investigations addressing the mechanisms underlying the development of CV complications and poor outcome in such cohort of patients are still few and controversial. Given the importance of a personalized approach against chemotherapy-induced cardiomyopathy, this review summarizes our current knowledge on the pathophysiology of chemotherapy-induced cardiomyopathy and its association with obesity and type 2 diabetes. Along with clinical evidences, future perspectives of preclinical research around this field and its role in addressing important open questions, including the development of more proactive strategies for prevention, and treatment of cardiotoxicity during and after chemotherapy in the presence of metabolic diseases, is also presented.

Insulin-like growth factor-1, metabolic abnormalities, and pathological complete remission rate in HER2-positive breast cancer patients receiving neoadjuvant therapy

Purpose: HER2-positive breast cancer (BC) achieving pathological complete remission (pCR) after neoadjuvant therapy (NAT) had a superior disease outcome. Dysmetabolism and stimulation of insulin-like growth factor 1 (IGF-1)-axis would increase BC risk, but we are lacking data for their association with pCR in HER2-positive+ BC. We aim to evaluate the pCR predictive value of above factors in HER2-positive BC patients receiving NAT.

Patients and methods: HER2-positive BC patients receiving NAT ± trastuzumab were retrospectively included between January 2013 and December 2016. Data were compared between baseline at biopsy and surgery. Median value of IGF-1 expression was used as cutoff value to classify patients into low or high group. pCR was defined as no residual invasive carcinoma in breast and axilla.

Results: Overall, 101 patients were included. Metabolic syndrome was diagnosed in 29 (28.71%) with an average of 1.71±1.51 metabolic disorders at baseline, significantly increased after NAT (2.12±1.54, P<0.001). Lipid metabolism factors, including triglycerides, TC, HDL-C and LDL-C significantly worsened after NAT (all P<0.05). Average post-NAT IGF-1 was 196.14±86.03 ng/mL (vs preNAT 186.41±75.03 ng/mL, P=0.182). pCR was achieved in 29 (28.71%) patients. pCR rate was 40.00% and 17.65% for those with low or high preIGF-1 level (P=0.013). Multivariate analysis found that low IGF-1 expression, but not any other metabolic variable, was significantly associated with higher pCR rate in whole population (OR: 3.83, 95%CI: 1.32–11.11, P=0.014) or in patients receiving NAT + trastuzumab (OR: 3.93, 95%CI: 1.13–13.63, P=0.031). With a median follow-up of 29.03 (range: 10.42–56.98) months, IGF-1 level was not associated with overall survival (P=0.328) or disease-free survival (P=0.288).

Conclusion: Low IGF-1 level was related with higher pCR rate in HER2-positive BC patients receiving NAT, which deserves further clinical evaluation.

Key metabolic parameters change significantly in early breast cancer survivors: an explorative PILOT study

Background

With increasing number of breast cancer survivors, more attention is drawn to long-term consequences of curative cancer treatment. Adjuvant treatment of breast cancer patients is associated with several unfavorable medical conditions, including dyslipidemia, insulin resistance, and obesity, potentially leading to cardiovascular disease and/or the metabolic syndrome. The aim of this explorative study is to investigate metabolic side effects of adjuvant treatment in breast cancer patients.

Methods

A cohort of 13 premenopausal and 20 postmenopausal women with early stage breast cancer were extensively examined prior to, immediately after and 1 year after ended adjuvant chemotherapy and compared with healthy controls (N = 36) matched by age and menopausal status. Repeated examinations included: anthropometric measures, DEXA scans, 24-h blood pressure measurements, and blood samples [high sensitivity CRP, lipid profile and glucose metabolism, including homeostatic model assessment (HOMA)].

Results

At baseline, breast cancer patients were similar to healthy controls regarding all measures. From baseline to 1-year post-treatment specific components of the metabolic syndrome increased significantly in premenopausal breast cancer patients; body fat (P = 0.01), triglycerides (P = 0.03), waist circumference (P = 0.008) and diastolic blood pressure (P = 0.04). In postmenopausal patients, waist circumference also increased significantly (P = 0.03), and High density lipoprotein (HDL) cholesterol decreased significantly (P = 0.05).

Conclusions

Specific components of the metabolic syndrome changed significantly during chemotherapy in early stage breast cancer patients. After 1 year, several key parameters remained pathologically changed. Premenopausal breast cancer patients seemed to be especially prone to develop these unfavorable changes.

Trial registration ClinicalTrial.gov, registration number NCT02652975. Registered 15 December 2015—Retrospectively registered, https://clinicaltrials.gov/.

Effect of chemotherapy and aromatase inhibitors in the adjuvant treatment of breast cancer on glucose and insulin metabolism-A systematic review

INTRODUCTION

Breast cancer (BC) is the most common cancer among women worldwide. With increasing survival rates, focus has expanded to long-term adverse effects of adjuvant chemotherapy and/or aromatase inhibitors. Weight gain during chemotherapy has been well documented, but the underlying mechanisms remain unclear. A change in glucose and insulin metabolism is a possible consequence.

METHODS

We searched PubMed on the 4th of May 2018, and found eight articles that compared measurements of glucose and insulin before and after chemotherapy and/or aromatase inhibitors in woman with BC.

RESULTS

A general trend of increased glucose and insulin is seen and likely to be caused by weight gain and/or changes in body composition as a consequence of adjuvant treatment of BC.

DISCUSSION

Due to methodological limitations including short follow-up times and small sample sizes, further studies are required to better describe metabolic consequences of adjuvant chemotherapy and/or aromatase inhibitors. Future studies could help identify patients in high-risk of developing cardiometabolic disease after BC treatment.

Status of lipid and lipoprotein in female breast cancer patients at initial diagnosis and during chemotherapy

Background

The lipid profile status among breast cancer patients at initial diagnosis and during chemotherapy remain controversial. The aim of this study is to study the status of lipid and lipoprotein in female breast cancer patients at initial diagnosis and during chemotherapy.

Methods

We conducted a retrospective cohort study of the status of the lipid and lipoprotein in 1054 primarily diagnosed breast cancer patients and 2483 normal controls with age stratification, from July 2015 to October 2016. At the same time, the status of lipid and lipoprotein were also analyzed among 394 breast cancer patients before and after adjuvant chemotherapy.

Results

The incidence of dyslipidemia was significantly lower in breast cancer group(42.98%) compared to normal group(58.28%)(P < 0.001). The levels of total cholesterol (TC), triglycerides (TG), HDL cholesterol (HDL-C), LDL cholesterol (LDL-C) among breast cancer group were significantly lower compared to normal control group (P < 0.05). With age stratification, the levels of TC and LDL-C in breast cancer group were still significantly lower than those in control group (P < 0.001). And the levels of TC, TG, LDL-C, apolipoprotein B were significantly higher among post chemotherapeutic patients compared to prechemotherapeutic patients, however HDL-C and Apo-A1 levels were contrary.

Conclusions

Breast cancer patients have lower incidence of dyslipidemia compared to normal populations. However, the situation of dyslipidemia may become worsened after chemotherapy. Therefore, lipid monitoring and dyslipidemia prevention and treatment should be conducted for breast cancer patients at initial diagnosis and during chemotherapy.

An observational study to examine changes in metabolic syndrome components in patients with breast cancer receiving neoadjuvant or adjuvant chemotherapy

BACKGROUND

The authors sought to determine the effect of chemotherapy on the development of metabolic syndrome (MetS) in premenopausal and postmenopausal women undergoing (neo)adjuvant therapy for early‐stage breast cancer.

METHODS

A total of 86 women with early‐stage (AJCC stage I‐III) breast cancer who were free from clinically diagnosed MetS (defined as 3 of 5 components of MetS) were prospectively tested for the presence of the 5 components of MetS within 1 week before initiating and after completing (neo)adjuvant chemotherapy. The 5 components of MetS measured were waist circumference; blood pressure; and fasting levels of blood glucose, triglycerides, and high‐density lipoprotein cholesterol. Anthropometrics (body weight, percentage body fat, fat mass), lipid profile (total cholesterol, low‐density lipoprotein cholesterol), glucose metabolism (insulin, homeostatic model assessment of insulin resistance, glycated hemoglobin), and inflammation (C‐reactive protein) also were examined before initiating and after completing treatment.

RESULTS

The current study included 46 premenopausal and 40 postmenopausal women. All individual MetS components and the overall MetS score were found to be statistically significantly increased (P<.01) after chemotherapy. Body weight, percentage body fat, fat mass, lipids, glucose metabolism, and inflammation also were found to be statistically significantly increased (P<.01).

CONCLUSIONS

A 12‐week to 18‐week course of chemotherapy appears to statistically significantly increase MetS and related anthropometrics, biomarkers of glucose metabolism, and inflammation in patients with early‐stage breast cancer with no preexisting MetS. Lifestyle interventions such as diet and exercise may be preventive approaches for use during chemotherapy to reduce the onset of MetS in patients with breast cancer. Cancer 2016. © 2016 The Authors. Cancer published by Wiley Periodicals, Inc. on behalf of American Cancer Society. Cancer 2016;122:2646–2653. © 2016 American Cancer Society.

Patients with breast cancer who receive (neo)adjuvant chemotherapy experience an impaired metabolic presentation as noted by worsened components of metabolic syndrome, anthropometrics, and biomarkers of glucose metabolism. Lifestyle interventions such as diet and exercise may be preventive approaches for use during chemotherapy to reduce the onset of metabolic syndrome in patients with breast cancer.

Obesity and cancer: mechanistic insights from transdisciplinary studies

Obesity is associated with a range of health outcomes that are of clinical and public health significance, including cancer. Herein, we summarize epidemiologic and preclinical evidence for an association between obesity and increased risk of breast and prostate cancer incidence and mortality. Moreover, we describe data from observational studies of weight change in humans and from calorie-restriction studies in mouse models that support a potential role for weight loss in counteracting tumor-promoting properties of obesity in breast and prostate cancers. Given that weight loss is challenging to achieve and maintain, we also consider evidence linking treatments for obesity-associated co-morbidities, including metformin, statins and non-steroidal anti-inflammatory drugs, with reduced breast and prostate cancer incidence and mortality. Finally, we highlight several challenges that should be considered when conducting epidemiologic and preclinical research in the area of obesity and cancer, including the measurement of obesity in population-based studies, the timing of obesity and weight change in relation to tumor latency and cancer diagnosis, and the heterogeneous nature of obesity and its associated co-morbidities. Given that obesity is a complex trait, comprised of behavioral, epidemiologic and molecular/metabolic factors, we argue that a transdisciplinary approach is the key to understanding the mechanisms linking obesity and cancer. As such, this review highlights the critical need to integrate evidence from both epidemiologic and preclinical studies to gain insight into both biologic and non-biologic mechanisms contributing to the obesity-cancer link.