Impact of Body Mass Index, Weight Gain, and Metabolic Disorders on Survival and Prognosis in Patients with Breast Cancer Who Underwent Chemotherapy
Breast cancer remains the most common malignant tumor among women globally, with significant implications for public health. In 2020, there were 2.3 million new cases of breast cancer, accounting for 11.7% of all malignancies and 685,000 deaths worldwide. In China, the incidence and mortality rates of breast cancer have been increasing annually from 2000 to 2015, with 304,000 new cases and 70,000 deaths reported in 2015. Chemotherapy is a critical systemic treatment for breast cancer, improving long-term survival rates. However, chemotherapy is often associated with weight gain and metabolic disorders, which can negatively impact patient prognosis, increasing risks of recurrence, metastasis, and reduced survival rates.
This study aimed to explore the prognostic effects of body mass index (BMI), weight gain, and metabolic disorders on the overall survival (OS) and prognosis of patients with breast cancer who underwent chemotherapy. The research was conducted retrospectively, analyzing data from patients treated at the Beijing Cancer Hospital Breast Cancer Center from January to December 2010, with follow-up until August 2020. A total of 438 patients with stages I to III breast cancer met the inclusion criteria, with 49 (11.19%) deaths and 82 (18.72%) cases of tumor recurrence and metastasis recorded by the end of the follow-up period.
Weight and Metabolic Changes During Chemotherapy
The study found that chemotherapy led to significant weight gain in patients with breast cancer. Among 422 patients with complete weight records, 302 (71.6%) had stable weight, 30 (7.1%) experienced weight loss of more than 5%, and 90 (21.3%) gained 5% or more weight. The average body weight increased from 63.73 kg at diagnosis to 64.44 kg after chemotherapy. Similarly, the average BMI increased from 24.93 kg/m² to 25.23 kg/m². The proportion of overweight and obese patients also rose from 46.4% at diagnosis to 51.2% after chemotherapy.
Metabolic disorders were prevalent among the patients, with 277 (63.3%) having metabolic disorders at diagnosis and 321 (73.3%) developing them after chemotherapy. The number of patients with three or more metabolic disorders increased from 56 (12.8%) at diagnosis to 74 (16.9%) after chemotherapy. Specific metabolic indicators, such as high triglyceride (TG) levels and low high-density lipoprotein cholesterol (HDL-C) levels, showed significant increases post-chemotherapy. For instance, the proportion of patients with high TG levels rose from 32.1% to 53.5%, and those with low HDL-C levels increased from 6.8% to 17.2%.
Impact on Overall Survival and Prognosis
The study revealed that the 1-, 3-, 5-, and 10-year OS rates for patients with breast cancer were 97.5%, 94.0%, 91.9%, and 88.4%, respectively. The median survival time was 109.29 months. However, BMI categories and weight changes did not significantly affect OS. In contrast, metabolic disorders, particularly low HDL-C levels at diagnosis, had a significant negative impact on survival. Patients with low HDL-C levels at diagnosis had a shorter OS time compared to those with normal levels. Multivariate Cox regression analysis confirmed that low HDL-C levels at diagnosis were an independent risk factor for OS, with a hazard ratio (HR) of 2.775.
Furthermore, metabolic disorders after chemotherapy were identified as risk factors for poor prognosis. Patients with metabolic disorders post-chemotherapy had a higher likelihood of tumor recurrence or metastasis, with an odds ratio (OR) of 1.514. Low HDL-C levels at diagnosis were also associated with an increased risk of death, with an OR of 4.010.
Discussion
The findings of this study highlight the complex relationship between weight, metabolic health, and breast cancer prognosis. While chemotherapy is essential for improving survival rates, it often leads to weight gain and exacerbates metabolic disorders, which can negatively impact patient outcomes. The study underscores the importance of monitoring and managing metabolic health in breast cancer patients undergoing chemotherapy.
The increase in weight and BMI observed in this study is consistent with previous research, which has shown that weight gain during chemotherapy is a common issue among breast cancer patients. However, the impact of weight gain on OS and prognosis remains controversial. Some studies have found that weight gain is associated with poorer outcomes, while others, including this study, did not find a significant effect. This discrepancy may be due to differences in study populations, follow-up periods, and methodologies.
Metabolic disorders, particularly low HDL-C levels, emerged as significant predictors of poor prognosis in this study. Low HDL-C levels are associated with a more aggressive tumor profile and increased inflammation, which can promote cancer progression and metastasis. The study’s findings align with previous research that has identified metabolic syndrome and its components as risk factors for breast cancer recurrence and mortality.
The study also identified other clinical factors that influenced OS, including menopausal status, lymph node status, and estrogen receptor (ER) status. Postmenopausal patients, those with positive lymph nodes, and those with negative ER status had worse survival outcomes. These findings are consistent with the broader literature on breast cancer prognosis.
Limitations and Future Research
This study has several limitations. The retrospective design and reliance on hospital records may have introduced biases and limited the availability of detailed data on body fat distribution and other metabolic indicators. Additionally, the follow-up period for weight changes was relatively short, which may have affected the ability to detect long-term impacts on survival and prognosis.
Future research should focus on prospective studies with longer follow-up periods to better understand the patterns of weight changes and metabolic disturbances during chemotherapy. Including more comprehensive measures of obesity, such as waist circumference and body fat distribution, could provide additional insights into the relationship between metabolic health and breast cancer outcomes. Furthermore, interventions aimed at managing weight and metabolic health during chemotherapy should be explored to improve patient prognosis.
Conclusion
Chemotherapy for breast cancer is associated with weight gain and the exacerbation of metabolic disorders, which can negatively impact patient survival and prognosis. While BMI categories and weight changes did not significantly affect OS in this study, low HDL-C levels at diagnosis and metabolic disorders after chemotherapy were identified as important risk factors for poor outcomes. These findings highlight the need for careful monitoring and management of metabolic health in breast cancer patients undergoing chemotherapy to improve their long-term prognosis.
doi.org/10.1097/CM9.0000000000001988
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