Background:
Quality assurance (QA) in modern radiotherapy (RT) aims to detect inconsistencies that might adversely affect treatment outcome. Across communities, there are significant variations in the practice of QA reviews; here, we describe a single institutional experience on the breast QA process.
Aim:
To report on the process and outcomes of our breast QA rounds, and identify factors that associate with plan modifications.
Methods:
All curative breast RT plans were presented at weekly QA rounds prior to commencement of treatment. Comments regarding the plan were recorded in real-time, including type of modifications: no (A), minor (B), or major (C).
Results:
From January 1, 2010 to December 31, 2012, 2223 breast cases were reviewed; only 47 (2.1%) underwent a minor change (B); 52 (2.3%) required a major modification (C). The most common changes involved volume coverage, seroma contouring, addition of a boost, or use of bolus. On univariate analysis, plans using more than 2 fields (OR 2.57, p=0.0011), triple negative disease (OR 2.49, p=0.017), axillary node dissection (OR 1.76, p=0.045), and tumour size more than 2 cm (OR 2.01, p=0.025) were significantly associated with category C. After multivariate analysis, only the number of fields (OR 2.09, p=0.017), and triple negative disease (OR 2.34, p=0.027) remained significant. For cases who were node negative, margin negative, and only 2 fields with no boosts (n=561), modifications were required in only 0.89% of instances.
Conclusions:
It is feasible to conduct weekly QA review for all radically treated breast cancer cases in a busy cancer centre. Techniques with more than 2 fields, and triple negative disease predicted for a higher likelihood of plan modifications. Conversely, less than 1% of node-negative cases with clear margins, treated with a 2-field technique and no boosts, required adjustment. These observations will contribute to streamlining future breast QA rounds.