Chemotherapy dose reductions in obese patients with colorectal cancer

Post-diagnosis adiposity and colorectal cancer prognosis: A Global Cancer Update Programme (CUP Global) systematic literature review and meta-analysis

The adiposity influence on colorectal cancer prognosis remains poorly characterised. We performed a systematic review and meta-analysis on post-diagnosis adiposity measures (body mass index [BMI], waist circumference, waist-to-hip ratio, weight) or their changes and colorectal cancer outcomes. PubMed and Embase were searched through 28 February 2022. Random-effects meta-analyses were conducted when at least three studies had sufficient information. The quality of evidence was interpreted and graded by the Global Cancer Update Programme (CUP Global) independent Expert Committee on Cancer Survivorship and Expert Panel. We reviewed 124 observational studies (85 publications). Meta-analyses were possible for BMI and all-cause mortality, colorectal cancer-specific mortality, and cancer recurrence/disease-free survival. Non-linear meta-analysis indicated a reverse J-shaped association between BMI and colorectal cancer outcomes (nadir at BMI 28 kg/m2). The highest risk, relative to the nadir, was observed at both ends of the BMI distribution (18 and 38 kg/m2), namely 60% and 23% higher risk for all-cause mortality; 95% and 26% for colorectal cancer-specific mortality; and 37% and 24% for cancer recurrence/disease-free survival, respectively. The higher risk with low BMI was attenuated in secondary analyses of RCTs (compared to cohort studies), among studies with longer follow-up, and in women suggesting potential methodological limitations and/or altered physiological state. Descriptively synthesised studies on other adiposity-outcome associations of interest were limited in number and methodological quality. All the associations were graded as limited (likelihood of causality: no conclusion) due to potential methodological limitations (reverse causation, confounding, selection bias). Additional well-designed observational studies and interventional trials are needed to provide further clarification.

Obesity and Cancer: A Current Overview of Epidemiology, Pathogenesis, Outcomes, and Management

BACKGROUND

Obesity or excess body fat is a major global health challenge that has not only been associated with diabetes mellitus and cardiovascular disease but is also a major risk factor for the development of and mortality related to a subgroup of cancer. This review focuses on epidemiology, the relationship between obesity and the risk associated with the development and recurrence of cancer and the management of obesity.

METHODS

A literature search using PubMed and Google Scholar was performed and the keywords 'obesity' and cancer' were used. The search was limited to research papers published in English prior to September 2022 and focused on studies that investigated epidemiology, the pathogenesis of cancer, cancer incidence and the risk of recurrence, and the management of obesity.

RESULTS

About 4-8% of all cancers are attributed to obesity. Obesity is a risk factor for several major cancers, including post-menopausal breast, colorectal, endometrial, kidney, esophageal, pancreatic, liver, and gallbladder cancer. Excess body fat results in an approximately 17% increased risk of cancer-specific mortality. The relationship between obesity and the risk associated with the development of cancer and its recurrence is not fully understood and involves altered fatty acid metabolism, extracellular matrix remodeling, the secretion of adipokines and anabolic and sex hormones, immune dysregulation, and chronic inflammation. Obesity may also increase treatment-related adverse effects and influence treatment decisions regarding specific types of cancer therapy. Structured exercise in combination with dietary support and behavior therapy are effective interventions. Treatment with glucagon-like peptide-1 analogues and bariatric surgery result in more rapid weight loss and can be considered in selected cancer survivors.

CONCLUSIONS

Obesity increases cancer risk and mortality. Weight-reducing strategies in obesity-associated cancers are important interventions as a key component of cancer care. Future studies are warranted to further elucidate the complex relationship between obesity and cancer with the identification of targets for effective interventions.

Chemotherapy and Anticancer Drugs Adjustment in Obesity: A Narrative Review

BACKGROUND

Obese individuals have higher rates of cancer incidence and cancer- related mortality. The worse chemotherapy outcomes observed in this subset of patients are multifactorial, including the altered physiology in obesity and its impact on pharmacokinetics, the possible increased risk of underdosing, and treatment-related toxicity.

AIMS

The present review aimed to discuss recent data on physiology, providing just an overall perspective and pharmacokinetic alterations in obesity concerning chemotherapy. We also reviewed the controversies of dosing adjustment strategies in adult and pediatric patients, mainly addressing the use of actual total body weight and ideal body weight.

METHODS

This narrative review tried to provide the best evidence to support antineoplastic drug dosing strategies in children, adolescents, and adults.

RESULTS

Cardiovascular, hepatic, and renal alterations of obesity can affect the distribution, metabolism, and clearance of drugs. Anticancer drugs have a narrow therapeutic range, and variations in dosing may result in either toxicity or underdosing. Obese patients are underrepresented in clinical trials that focus on determining recommendations for chemotherapy dosing and administration in clinical practice. After considering associated comorbidities, the guidelines recommend that chemotherapy should be dosed according to body surface area (BSA) calculated with actual total body weight, not an estimate or ideal weight, especially when the intention of therapy is the cure.

CONCLUSION

The actual total body weight dosing appears to be a better approach to dosing anticancer drugs in both adults and children when aiming for curative results, showing no difference in toxicity and no limitation in treatment outcomes compared to adjusted doses.

Review article: obesity and colorectal cancer

BACKGROUND

Obesity is a growing global public health problem. More than half the European and North American population is overweight or obese. Colon and rectum cancers are still the second leading cause of cancer death worldwide, and epidemiological data support an association between obesity and colorectal cancers (CRCs).

AIM

To review the literature on CRC epidemiology in obese subjects, assessing the effects of obesity, including childhood or maternal obesity, on CRC, diagnosis, management, and prognosis, and discussing targeted prophylactic measures.

METHOD

We searched PubMed for obesity/overweight/metabolic syndrome and CRC. Other key words included 'staging', 'screening', 'treatment', 'weight loss', 'bariatric surgery' and 'chemotherapy'.

RESULTS

In Europe, about 11% of CRCs are attributed to overweight and obesity. Epidemiological data suggest that obesity is associated with a 30%-70% increased risk of colon cancer in men, the association being less consistent in women. Visceral fat or abdominal obesity seems to be of greater concern than subcutaneous fat obesity, and any 1 kg/m² increase in body mass index confers more risk (hazard ratio 1.03). Obesity might increase the likelihood of recurrence or mortality of the primary cancer and may affect initial management, including accurate staging. The risk maybe confounded by different factors, including lower adherence to organised CRC screening programmes. It is unclear whether bariatric surgery helps reduce rectal cancer risk.

CONCLUSIONS

Despite a growing body of evidence linking obesity to CRC, many questions remain unanswered, including whether we should screen patients with obesity earlier or propose prophylactic bariatric surgery for certain patients with obesity.

Antineoplastic dosing in overweight and obese cancer patients: an Associazione Italiana Oncologia Medica (AIOM)/Associazione Medici Diabetologi (AMD)/Società Italiana Endocrinologia (SIE)/Società Italiana Farmacologia (SIF) multidisciplinary consensus position paper

Most anticancer molecules are administered in body-size-based dosing schedules, bringing up unsolved issues regarding pharmacokinetic data in heavy patients. The worldwide spread of obesity has not been matched by improved methods and strategies for tailored drug dosage in this population. The weight or body surface area (BSA)-based approaches may fail to fully reflect the complexity of the anthropometric features besides obesity in cancer patients suffering from sarcopenia. Likewise, there is a lack of pharmacokinetic data on obese patients for the majority of chemotherapeutic agents as well as for new target drugs and immunotherapy. Therefore, although the available findings point to the role of dose intensity in cancer treatment, and support full weight-based dosing, empirical dose capping often occurs in clinical practice in order to avoid toxicity. Thus a panel of experts of the Associazione Italiana Oncologia Medica (AIOM), Associazione Medici Diabetologi (AMD), Società Italiana Endocrinologia (SIE), and Società Italiana Farmacologia (SIF), provides here a consensus statement for appropriate cytotoxic chemotherapy and new biological cancer drug dosing in obese patients.

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The worldwide spread of obesity is an emerging challenge also in cancer patients

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Weight or BSA-based approaches do not adequately address the critical issue of optimal dosing for cancer drugs under obesity

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Empirical dose capping is often employed in clinical practice to avoid toxicities among overweight and obese patients

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There is a lack of clinical and pharmacokinetic studies in this population

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Clinical practice recommendations should guide suitable dosing of cytotoxic and biological cancer drugs in obese patients

Appropriate Systemic Therapy Dosing for Obese Adult Patients With Cancer: ASCO Guideline Update

PURPOSE

To provide recommendations for appropriate dosing of systemic antineoplastic agents in obese adults with cancer.

METHODS

A systematic review of the literature collected evidence regarding dosing of chemotherapy, immunotherapy, and targeted therapies in obese adults with cancer. PubMed and the Cochrane Library were searched for randomized controlled trials, meta-analyses, or cohort studies published from November 1, 2010, through March 27, 2020. ASCO convened an Expert Panel to review the evidence and formulate recommendations.

RESULTS

Sixty studies, primarily retrospective, were included in the review. Overall, the evidence supported previous findings that obese adult patients tolerate full, body-size-based dosing of chemotherapy as well as nonobese patients. Fewer studies have addressed the dosing of targeted therapies and immunotherapies in relation to safety and efficacy in obese patients.

RECOMMENDATIONS

The Panel continues to recommend that full, weight-based cytotoxic chemotherapy doses be used to treat obese adults with cancer. New to this version of the guideline, the Panel also recommends that full, approved doses of immunotherapy and targeted therapies be offered to obese adults with cancer. In the event of toxicity, the consensus of the Panel is that dose modifications of systemic antineoplastic therapies should be handled similarly for obese and nonobese patients. Important areas for future research include the impact of sarcopenia and other measures of body composition on optimal antineoplastic dosing, and more customized dosing based on pharmacokinetic or pharmacogenetic factors.Additional information is available at www.asco.org/supportive-care-guidelines.

Body surface area capping may not improve cytotoxic drugs tolerance

Capping body surface area (BSA) at 2 m² is a routine clinical practice. It aims at reducing toxicities in over 2 m² BSA patients. 455,502 computerized chemotherapy prescriptions made between 2011 and 2017 were taken from BPC software. Chemotherapy computerized order entry is created by a senior physician prescribers before patient consultation. Only prescriptions with dose calculation involving BSA were selected. 51,179 chemotherapy prescriptions were analyzed; corresponding to 7206 patients who received intravenous chemotherapy. The number of chemotherapy prescriptions in over 2 m² BSA patients was nearly the same in the hematology as in the oncology departments. But, 79.1% of prescriptions were capped at 2 m² in the oncology department contrary to 21.9% in the hematology department. Practices analysis showed more dose limitation in palliative situations in both departments. Unexpectedly, 6.53% of capped prescriptions were performed in patients with normal BMI. The patients who received capped doses of chemotherapy had neither fewer dose reductions due to toxicity nor deterioration of their general condition. Capping did not induce fewer dose reductions in patients with BSA greater than 2 m². Prospective studies in this population are needed to standardize chemotherapy administration in population with BSA > 2 m².

The impact of anthropometric parameters on colorectal cancer prognosis: A systematic review and meta-analysis

BACKGROUND & AIMS

Our study aims to clarify the relationship between weight parameters and colorectal cancer outcomes.

METHODS

NCBI, Embase, Cochrane, and Web of Science were searched from inception to December 2019. Studies reporting colorectal cancer (CRC) mortality, recurrence, disease-free survival, overall survival, overall mortality stratified by pre-diagnosis BMI or post-diagnosis weight change, were included in the analysis. Random effects analysis was performed for all outcomes, with heterogeneity assessed by the I² statistic.

RESULTS

Our meta-analysis included 45 studies encompassing 607,266 patients. Obesity was associated with increased odds of overall mortality and CRC-specific mortality compared to normal weight (p < 0.001). Patients with underweight BMI had increased odds of CRC-specific mortality compared to normal BMI but were not significantly different from obese BMI.

CONCLUSIONS

Obese and underweight BMI are associated with increased CRC-specific and overall mortality compared to normal BMI. Long term prognosis was similar for patients with obese and underweight BMI.

Overcoming barriers to implementing precision dosing with 5-fluorouracil and capecitabine

Despite advances in targeted cancer therapy, the fluoropyrimidines 5-fluorouracil (5FU) and capecitabine continue to play an important role in oncology. Historically, dosing of these drugs has been based on body surface area. This approach has been demonstrated to be an imprecise way to determine the optimal dose for a patient. Evidence in the literature has demonstrated that precision dosing approaches, such as DPD enzyme activity testing and, in the case of intravenous 5FU, pharmacokinetic-guided dosing, can reduce toxicity and yield better patient outcomes. However, despite the evidence, there has not been uniform adoption of these approaches in the clinical setting. When a drug such as 5FU has been used clinically for many decades, it may be difficult to change clinical practice. With the aim of facilitating change of practice, issues and barriers to implementing precision dosing approaches for 5FU and capecitabine are identified and discussed with possible solutions proposed.

Impact of dose-capping chemotherapy in concurrent chemoradiotherapy in rectal cancer patients

INTRODUCTION

The study evaluated the effect of chemotherapy dose-capping on disease recurrence, toxicity and survival of rectal cancer patients treated with chemoradiotherapy (CRT).

METHODS

601 consecutive rectal cancer patients treated with concurrent CRT were retrospectively analysed. Dose-capped patients were defined as having a body surface area (BSA) ≥2.0 m² and who received <95% full weight-based chemotherapy dose. Binary logistic regression was used to study the factors associated with the outcome variables (capped vs. uncapped). Kaplan-Meier estimation evaluated significant predictors of survival.

RESULTS

The median follow-up time was 7.54 years. The rate of disease recurrence was significantly higher in dose-capped patients (35%) compared to those without dose-capping (24%, P = 0.016). The adjusted odds ratio for dose-capped patients experiencing recurrence was 1.64 compared to uncapped patients (95% CI, 1.10-2.43). Overall, dose-capped patients were less likely to experience significant toxicity requiring dose reduction and/or treatment break when compared to uncapped patients (15% and 28% respectively, P = 0.008).There was significant differences in PFS between capped and uncapped group (77% vs. 85%; P = 0.017). The 5-year OS in the capped group was 75.0%, and 80% in the uncapped group (P = 0.149).

CONCLUSIONS

Rectal cancer patients treated with dose-capped CRT were at increased risk of disease recurrence. Patients dosed by actual BSA did experience excessive toxicity compared to dose-capped group. We recommend that chemotherapy dose-capping based on BSA should not be practiced in rectal cancer patients undergoing CRT.

Obesity and Cancer Treatment Outcomes: Interpreting the Complex Evidence

A wealth of epidemiological evidence, combined with plausible biological mechanisms, present a convincing argument for a causal relationship between excess adiposity, commonly approximated as body mass index (BMI, kg/m²), and incident cancer risk. Beyond this relationship, there are a number of challenges posed in the context of interpreting whether being overweight (BMI 25.0-29.9 kg/m²) or obese (BMI ≥ 30.0 kg/m²) adversely influences disease progression, cancer mortality and survival. Elevated BMI (≥ 25.0 kg/m²) may influence treatment selection of, for example, the approach to surgery; the choice of chemotherapy dosing; the inclusion of patients into randomised clinical trials. Furthermore, the technical challenges posed by an elevated BMI may adversely affect surgical outcomes, for example, morbidity (increasing the risk of surgical site infections), reduced lymph node harvest (and subsequent risk of under-staging and under-treatment) and increased risk of margin positivity. Suboptimal chemotherapy dosing, associated with capping chemotherapy in obese patients as an attempt to avoid excess toxicity, might be a driver of poor prognostic outcomes. By contrast, the efficacy of immune checkpoint inhibition may be enhanced in patients who are obese, although in turn, this observation might be due to reverse causality. So, a central research question is whether being overweight or obese adversely affects outcomes either directly through effects of cancer biology or whether adverse outcomes are mediated through indirect pathways. A further dimension to this complex relationship is the obesity paradox, a phenomenon where being overweight or obese is associated with improved survival where the reverse is expected. In this overview, we describe a framework for evaluating methodological problems such as selection bias, confounding and reverse causality, which may contribute to spurious interpretations. Future studies will need to focus on prospective studies with well-considered methodology in order to improve the interpretation of causality.

Outcome of methotrexate treatment for ectopic pregnancies among obese women

OBJECTIVE

Single dose administration of methotrexate (MTX) is considered the first line of treatment in selected patients with an ectopic pregnancy (EP). However, data regarding MTX efficacy among obese patients is limited. We sought to investigate the efficacy of MTX single dose regimen among obese patients MATERIAL AND METHODS: A retrospective cohort study conducted at a gynecology department in a tertiary teaching hospital, between January 2010 and December 2018, including women diagnosed with an EP and treated by a single-dose regimen of MTX. We compared success rate and gestation characteristics between obese and non-obese women.

RESULTS

Overall, 195 women were treated with single-dose intramuscular MTX for EP during the study period. Of those, 31 women (15.9%) were obese (BMI ≥ 30 kg/m2) and the rest 164 (84.1%) were of normal body weight. Median MTX dosage for the obese group was 95 milligrams (IQR 91-104) vs. 83 milligrams (IQR 78-87) for the non-obese group. Treatment success rate of the overall cohort was 66.6% (130/195) and treatment success rate of single-dose MTX was comparable between the obese and non-obese groups (64.5% vs. 67.0%, p = 0.78). Obese patients were older as compared to non-obese (median age 33 vs. 29, p = 0.03). In multivariate logistic regression analysis, percentage hCG change from day 1 to day 4 was the only factor associated with treatment success (aOR 1.02; 95%CI 1.01, 1.04, p < 0.001).

CONCLUSION

Single-dose MTX treatment among obese patients diagnosed with ectopic pregnancy led to similar success rates as compared to non-obese patients.

Nutrition and cancer: evidence gaps and opportunities for improving knowledge

The Nutrition Society's 1st Annual Nutrition and Cancer Networking Conference brought together scientists from the fields of Nutrition, Epidemiology, Public Health, Medical Oncology and Surgery with representatives of the public, cancer survivors and cancer charities. Speakers representing these different groups presented the challenges to collaboration, how the needs of patients and the public can be met, and the most promising routes for future research. The conference programme promoted debate on these issues to highlight current gaps in understanding and barriers to generating and implementing evidence-based nutrition advice. The main conclusions were that the fundamental biology of how nutrition influences the complex cancer risk profiles of diverse populations needs to be better understood. Individual and population level genetics interact with the environment over a lifespan to dictate cancer risk. Large charities and government have a role to play in diminishing our current potently obesogenic environment and exploiting nutrition to reduce cancer deaths. Understanding how best to communicate, advise and support individuals wishing to make dietary and lifestyle changes, can reduce cancer risk, enhance recovery and improve the lives of those living with and beyond cancer.

Obesity and chemotherapy administration: between empiric and mathematic method review

Introduction: Obesity is a major risk factor for chronic disease and cancer development. Therapeutic management of obese patients with cancer is a real challenge for physician because of the alteration of antineoplastic pharmacokinetics parameters in this population. In routine clinical practices, chemotherapy doses in obese patients are arbitrarily capped or adjusted to an ideal weight to minimize excessive toxicities. Material and methods: The main goal of this review is to describe the current state of knowledge concerning the correlation between the adjustment of BSA (capping or ideal weight) and the rates of global toxicities and survival outcomes in obese patients under chemotherapy in different types of cancer. We searched in the Medline database (via PubMed) in order to identify all publications of literature reviews whose subject chemotherapy dosing in obese population. Results: Only a single study was pointing toward increased of global toxicities of full weight dosing. Furthermore, some studies suggests that the practice of limiting doses in overweight and obese patients may negatively influence the quality of care and outcomes in a constantly increasing population. Conclusion: This review highlights the lack of prospective studies focusing on chemotherapy methods of administration in obese patients. At this time, there is no prospective study comparing capping and full weight dose chemotherapy administration in obese patient population.

The impact of actual body weight-based chemotherapy dosing and body size on adverse events and outcome in older patients with breast cancer: Results from Cancer and Leukemia Group B (CALGB) trial 49907 (Alliance A151436)

OBJECTIVE

Actual weight-based (AWB) chemotherapy dosing is recommended for obese patients in the 2012 ASCO Clinical Practice Guideline. CALGB 49907, which utilized ABW-based adjuvant chemotherapy dosing, was a phase 3 trial in women age≥65years with early stage breast cancer, providing the opportunity to examine impact of such dosing on toxicities and outcome in older patients with breast cancer.

MATERIALS AND METHODS

Adverse event data were available for 615 of 633 enrolled patients. Objectives were to assess grade≥3 hematologic/non-hematologic toxicities by treatment arm, age, study entry BSA/BMI, and relapse-free (RFS) and overall survival (OS) by BSA/BMI.

RESULTS

The 615 patients were sub-grouped by BSA (quartiles) and standard BMI categories, with BMI underweight/normal weight categories combined. Overall, grade≥3 non-hematologic and hematologic toxicities occurred in 39.8% and 28.3% of patients, respectively. There were no significant differences in grade≥3 toxicities among BSA quartiles. However, more grade≥3 hematologic toxicities occurred in the underweight/normal weight BMI subgroup compared to overweight/obese subgroups (p=0.048). Type of chemotherapy and age had no impact on toxicity occurrence by BSA/BMI categories. RFS was superior in the 25th-50th BSA percentile patients in univariate analysis (p=0.042), as was OS in both univariate and multivariate analyses (p=0.007, p=0.009, respectively). No differences in RFS or OS were found by BMI categories.

CONCLUSION

Obesity was not correlated with adverse relapse or survival outcome, and grade≥3 toxicities were not greater with ABW-based dosing. This supports safety and efficacy of ABW-based dosing as per the 2012 ASCO clinical practice guideline. ClinicalTrials.gov Identifier: NCT00024102 (49907).

How to Manage the Obese Patient With Cancer

Purpose

Obesity (body mass index [BMI] ≥ 30 kg/m2) is common among patients with cancer. We reviewed management issues in the obese patient with cancer, focusing on how obesity influences treatment selection (including chemotherapy dosing), affects chemotherapy toxicity and surgical complications, and might be a treatment effect modifier.

Methods

The majority of evidence is drawn from observational studies and secondary analyses of trial data, typically analyzed in N × 3 BMI categories (normal weight, overweight, and obese) matrix structures. We propose a methodological framework for interpretation focusing on sample size and composition, nonlinearity, and unmeasured confounding.

Results

There is a common perception that obesity is associated with increased treatment-related toxicity. Accordingly, cytotoxic chemotherapy dose reduction is common in patients with elevated BMI. Contrary to this, there is some evidence that full dosing in obese patients does not result in increased toxicity. However, these data are from a limited number of regimens, and fail to fully capture cytotoxic drug pharmacodynamics and pharmacokinetic variability in obese patients. Among patients undergoing surgery, there is evidence that elevated BMI is associated with increased perioperative mortality and increased rates of infectious complications. A novel finding is that these relationships hold after surgery for malignancy, but not for benign indications. There are biologic plausibilities that obesity might be an effect modifier of treatment, but supporting evidence from clinical studies is inconsistent.

Conclusion

In line with the ASCO 2012 guidelines, chemotherapy dosing is probably best performed using actual body weight in obese patients. However, specific regimens known to be associated with increased toxicity in this group should be used with caution. There is no guidance on dose for obese patients treated with biologic agents. Currently, there are no specific recommendations for the surgical management of the obese patient with cancer.

Guidance on the management of diarrhoea during cancer chemotherapy

Diarrhoea induced by chemotherapy in cancer patients is common, causes notable morbidity and mortality, and is managed inconsistently. Previous management guidelines were based on poor evidence and neglect physiological causes of chemotherapy-induced diarrhoea. In the absence of level 1 evidence from randomised controlled trials, we developed practical guidance for clinicians based on a literature review by a multidisciplinary team of clinical oncologists, dietitians, gastroenterologists, medical oncologists, nurses, pharmacist, and a surgeon. Education of patients and their carers about the risks associated with, and management of, chemotherapy-induced diarrhoea is the foundation for optimum treatment of toxic effects. Adequate--and, if necessary, repeated--assessment, appropriate use of loperamide, and knowledge of fluid resuscitation requirements of affected patients is the second crucial step. Use of octreotide and seeking specialist advice early for patients who do not respond to treatment will reduce morbidity and mortality. In view of the burden of chemotherapy-induced diarrhoea, appropriate multidisciplinary research to assess meaningful endpoints is urgently required.

Incidence and outcomes of chemotherapy and radiation in morbidly obese patients with locally advanced lung and esophageal cancers: a single-institution experience

BACKGROUND

In 2012, the American Society of Clinical Oncology issued a guideline urging health care professionals to "routinely use an obese patient's actual body weight, rather than an ideal body weight or other estimate, to calculate the appropriate dose of nearly all chemotherapy drugs. " This guideline does not address dosages for patients who are morbidly obese (body mass index ≥ 40) and receiving concomitant chemotherapy and radiation.

METHODS

This report describes a single-institution experience intended to address the issue of appropriate dosages for this patient population.

RESULTS

Among 1,886 cancer patients who received curative thoracic radiation at the Mayo Clinic, 16 (0.8%) were morbidly obese and received concomitant chemotherapy and radiation. Charlson morbidity scores for the cohort ranged from 2 to 9, and 10 patients had esophageal cancer. Ten of 16 patients received an initial chemotherapy dose reduction, and 4 of these patients experienced major adverse events, including 1 death. Similarly, among the 6 patients who received full-dose chemotherapy at the beginning of treatment, 2 had major adverse events. Nine patients went on to have their cancers resected, but no differences in survival were apparent among patients who received initial dose reductions and those who did not.

CONCLUSIONS

This single-institution experience remains limited. However, in view of the severe toxicity observed in this cohort, chemotherapy dose reductions seem appropriate in specific instances. Clinicians should also consider prescribing newer chemotherapy regimens that may be better tolerated in morbidly obese patients with cancer.

Excess adiposity and survival in patients with colorectal cancer: a systematic review

Excess adiposity is an established risk factor for incident colorectal cancer (CRC) but whether this association extrapolates to poorer survival is unclear. We undertook a systematic review to examine relationships between measures of adiposity and survival in patients with CRC. For distinction, we included pre-diagnosis exposure and CRC-related mortality. We performed dose-response meta-analyses and assessed study quality using eight domains of bias. Six study categories were identified based on (i) timing of adiposity measurement relative to survival analysis time zero and (ii) clinical setting. Several types of adiposity measurements were reported; body mass index (BMI) was the commonest. For pre-diagnosis cohorts, baseline BMI negatively impacted on CRC-related mortality in men only (risk estimate per 5 kg m(-2)  = 1.19, 95% confidence intervals: 1.14-1.25). The other groups were pre-diagnosis BMI but diagnosis as time zero; population-based cohorts; treatment cohorts; observational analyses within adjuvant chemotherapy trials; patients with metastatic CRC - each had several biases (e.g. treatment selection, reverse causality) and sources of confounding (e.g. chemotherapy 'capping'). Overall, there was insufficient evidence for a strong link between adiposity and survival. These findings demonstrate an important principle: an established link between an exposure (here, adiposity) and increased cancer incidence does not necessarily extrapolate into an inferior post-treatment outcome.

Marginal effects of glucose, insulin and insulin-like growth factor on chemotherapy response in endothelial and colorectal cancer cells

Resistance to chemotherapy is a major clinical issue for patients with colorectal cancer. Obesity has been associated with a poorer outcome and is a possible mechanism of resistance. The aim of the present study was to investigate the effect of obesity-related factors on the cell response to standard chemotherapy in stromal and colorectal cancer cells. Viability was measured following the treatment of colorectal cancer cell lines (WiDr and SW620) and stromal cells (human microvascular endothelial cells) in vitro with 5-fluorouracil, irinotecan and oxaliplatin under obesity-related conditions [elevated levels of insulin, insulin-like growth factor-1 (IGF-1) and glucose] and compared with non-elevated conditions. Obesity-related conditions alone increased cell viability and in selected cases, accumulation of the transcription factor, hypoxia-inducible factor-1. However, these conditions did not consistently increase resistance to the chemotherapy agents tested. The combination of IGF-1 and extremely low-dose chemotherapy significantly induced cell viability in WiDr colorectal cancer cells. These in vitro results may have clinical importance in an environment of increasing rates of obesity and colorectal cancer, and the frequent under-dosing of obese cancer patients.

Predicting chemotherapeutic response and toxicity in colorectal cancer

SUMMARY While treatment for colorectal cancer has evolved significantly over the past 10 years with the introduction of active chemotherapeutic agents and targeted therapies, this has been at the cost of increased toxicity for patients; and significant financial burden for governments and patients. Predicting clinical outcomes, especially given the largely elderly patient population involved, is therefore paramount. This review seeks to summarize existing data regarding the prediction of response and toxicity to chemotherapy agents currently used in the treatment of colorectal cancer.