Validation of a nomogram for predicting the risk of lymphedema following contemporary treatment for breast cancer: a large multi-institutional study (KROG 20-05)

PURPOSE

We previously constructed a nomogram for predicting the risk of arm lymphedema following contemporary breast cancer treatment. This nomogram should be validated in patients with different background characteristics before use. Therefore, we aimed to externally validate the nomogram in a large multi-institutional cohort.

METHODS

Overall, 8835 patients who underwent breast cancer surgery during 2007-2017 were identified. Data of variables in the nomogram and arm lymphedema were collected. The nomogram was validated externally using C-index and integrated area under the curve (iAUC) with 1000 bootstrap samples and by calibration plots.

RESULTS

Overall, 1377 patients (15.6%) developed lymphedema. The median time from surgery to lymphedema development was 11.4 months. Lymphedema rates at 2, 3, and 5 years were 11.2%, 13.1%, and 15.6%, respectively. Patients with lymphedema had significantly higher body mass index (median, 24.1 kg/m² vs. 23.4 kg/m²) and a greater number of removed nodes (median, 17 vs. 6) and more frequently underwent taxane-based chemotherapy (85.7% vs. 41.9%), total mastectomy (73.1% vs. 52.1%), conventionally fractionated radiotherapy (71.9% vs. 54.2%), and regional nodal irradiation (70.7% vs 22.4%) than those who did not develop lymphedema (all P < 0.001). The C-index of the nomogram was 0.7887, and iAUC was 0.7628, indicating good predictive accuracy. Calibration plots confirmed that the predicted lymphedema risks were well correlated with the actual lymphedema rates.

CONCLUSION

This nomogram, which was developed using factors related to multimodal breast cancer treatment and was validated in a large multi-institutional cohort, can well predict the risk of breast cancer-related lymphedema.

Disparities in the Use of Sentinel Lymph Node Dissection for Early Stage Breast Cancer

BACKGROUND

Clinical trials have long established the long-term safety of omitting axillary lymph node dissection (ALND) after sentinel lymph node dissection (SLND) in patients with clinically node-negative early stage breast cancer. The variations in utilization of SLND and ALND in this patient population, however, are currently unknown.

METHODS

Adult female patients (40 years and older) within the National Cancer Database diagnosed with breast cancer between January 2013 and December 2015, who had clinical T1-T2 and N0 disease, and who underwent either SLND (with or without subsequent ALND) or ALND were included. Differences in utilization across race, ethnicity, insurance type, facility, and residential characteristics were assessed using multivariable logistic regression.

RESULTS

Overall, 271,689 patients were included, of which 26,527 (10%) received ALND and 245,162 (90%) underwent SLND. After adjusting for demographics and cancer characteristics, black (odds ratio [OR], 1.11; 95% confidence interval [95% CI], 1.06-1.17) and Hispanic women (OR, 1.16; 95% CI, 1.10-1.24) were more likely to receive ALND. Patients without health insurance (OR, 1.33; 95% CI, 1.19-1.47), compared with private health insurance, and those receiving treatment at community cancer centers (OR, 1.60; 95% CI, 1.53-1.67), compared with academic/research centers, were also more likely to receive ALND.

CONCLUSIONS

Although the vast majority of women undergo SLND, significant disparities exist in its utilization for early stage breast cancer, with traditionally underserved patients receiving unwarranted extensive axillary surgery. Increased patient and surgeon education is needed to decrease variations in care that can affect patient's quality of life.