Radiotherapy and Long-term Outcomes in Early Breast Cancer With SLNB Omission

Recurrence-free survival is defined as the time from study enrollment to the first occurrence of ipsilateral invasive breast recurrence, ipsilateral regional lymph node recurrence, distant metastasis, or breast cancer death. The 5-year recurrence-free survival rate will be estimated using the Kaplan-Meier method.

Axillary recurrence is defined as newly diagnosed breast cancer recurrence in the ipsilateral axillary lymph nodes after study enrollment. The 5-year cumulative incidence of axillary recurrence will be estimated.

Locoregional recurrence is defined as the first occurrence of one or more of the following after study enrollment: ipsilateral invasive breast recurrence; ipsilateral axillary lymph node recurrence; ipsilateral supraclavicular or infraclavicular lymph node recurrence; or ipsilateral internal mammary lymph node recurrence. The 5-year cumulative incidence will be estimated.

Distant metastasis is defined as breast cancer metastasis occurring in organs or non-regional lymph nodes outside the ipsilateral breast and ipsilateral regional lymph node regions. The 5-year cumulative incidence of the first distant metastasis after study enrollment will be estimated

Overall survival is defined as the time from study enrollment to death from any cause. The 5-year overall survival rate will be estimated using the Kaplan-Meier method.

The proportion of participants experiencing at least one grade 2 or higher acute radiotherapy-related adverse event will be assessed using the Common Terminology Criteria for Adverse Events (CTCAE), version 6.0. CTCAE grades range from 1 to 5, with higher grades indicating greater severity. Acute toxicity is defined as toxicity occurring from the start of radiotherapy through 90 days after completion of radiotherapy.

The proportion of participants experiencing at least one grade 2 or higher late radiotherapy-related adverse event will be assessed using the Common Terminology Criteria for Adverse Events (CTCAE), version 6.0. CTCAE grades range from 1 to 5, with higher grades indicating greater severity. Late toxicity is defined as toxicity newly occurring or persisting more than 90 days after completion of radiotherapy.

Global health status and quality of life will be assessed using the European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire Core 30 (EORTC QLQ-C30). The Global Health Status/Quality of Life scale is transformed to a score ranging from 0 to 100. A higher score indicates better global health status and quality of life. The change from baseline will be evaluated at each scheduled follow-up assessment.

Breast symptoms will be assessed using the Breast Symptoms scale of the European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire Breast Cancer Module 23 (EORTC QLQ-BR23). The score is transformed to a scale ranging from 0 to 100. A higher score indicates more severe breast symptoms and therefore a worse outcome. The change from baseline will be evaluated at each scheduled follow-up assessment.

Arm symptoms will be assessed using the Arm Symptoms scale of the European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire Breast Cancer Module 23 (EORTC QLQ-BR23). The score is transformed to a scale ranging from 0 to 100. A higher score indicates more severe arm symptoms and therefore a worse outcome. The change from baseline will be evaluated at each scheduled follow-up assessment.

Body image will be assessed using the Body Image scale of the European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire Breast Cancer Module 23 (EORTC QLQ-BR23). The score is transformed to a scale ranging from 0 to 100. A higher score indicates better body image and therefore a better outcome. The change from baseline will be evaluated at each scheduled follow-up assessment.