Minimizing the V105 in Breast Irradiation Leads to Better Treatment Outcomes: A Retrospective Study

Abstract

The aim of this study is to investigate what effects, if any, minimizing the V105 in whole breast irradiation has on cosmetic outcomes. Beginning July 2018, we implemented a quality measure for all breast treatment plans aimed at minimizing the V105. To that effect, a quality index, QI, is introduced and defined as follows: QI = V105/V95 A plan is deemed acceptable for treatment delivery if QI ≤ 0.3. The QI and clinical outcome of 33 consecutive breast patients treated between January 2017 and June 2018 were retrospectively reviewed and compared to 38 consecutive patients treated since QI was implemented. A three-level grading system is used to review the treating physician reported complications related to the treatment as stated in the follow-up notes: Grades I, II and III. Grade I, or good outcome, means nothing stands out in the follow-up note as complication related to the treatment. Grade II, or moderate, is assigned when a mild reaction to the treatment is reported while Grade III, or bad, indicates cases where the note describes significant irradiation related complications such as fibrosis. All patients were prescribed 4249.6 cGy in 16 fractions, or 5040 cGy in 28 fractions, followed by an electron boost to the tumor bed. The QI quality measure went from a mean of 0.5 prior to, to 0.24 post implementing the V105 minimization requirement. Using the three-level grading system described above, the results of our study are summarized in Table 1. For patients treated prior to QI implementation, the number of patients experiencing Grade III complications increases over time going from 15% at 1 month to 40% at 24 months. In the group of patients treated following the introduction of the QI, only one case of Grade III complication was reported at 1 month. At 6 months follow-up, there are no Grade III level outcomes reported while the proportion of Grade I level outcomes improve among the same group to reach 45. Grade III reported outcomes are equally distributed between patients receiving 4249.6 cGy and 5040 cGy. Based on our results so far, minimizing V105 does lead to better outcomes in breast radiation treatments. What’s more, they also seem to indicate that when such a volume is not minimized, patients that initially experienced moderate complications may see their severity increase over time.Abstract 2099; TableTreatment outcomes before and after implementing V105 minimization or QI ≤ 0.3Follow-up intervalBefore QI ImplementationAfter QI Implementation1 month6 months12 months24 months1 month6 months12 monthsNumber of Patients3322231038273Grade I18.18%9.09%30.43%50%28.95%44.44%100%Grade II66.67%63.64%39.13%10%68.42%55.56%0.0%Grade III15.15%27.27%30.43%40%2.63%0.0%0.0% Open table in a new tab