Post-mastectomy radiation therapy without usage of a bolus may be a reasonable option

Abstract

To clarify the efficacy and toxicity of post-mastectomy radiation therapy (PMRT) without usage of a bolus, we identified 129 consecutive patients who received PMRT at the National Cancer Center Hospital East between 2003 and 2012. Seven of the 129 patients who received breast reconstruction before PMRT were excluded. All patients received PMRT of 6 MV photons, without usage of a bolus. The median follow-up duration for all eligible patients was 47.7 months (range: 4.0–123.2). Local, locoregional and isolated locoregional recurrence was found in 12 (9.8%), 14 (11%) and 5 patients (4.1%), respectively. The 3- and 5-year cumulative incidence of local recurrence, locoregional recurrence and isolated locoregional recurrence was 9.2 and 10.7%, 10.8 and 12.4%, and 4.3 and 4.3%, respectively. Although Grade 2 dermatitis was found in 11 patients (9.0%), no Grade 3–4 dermatitis was found. On univariate analysis, only a non-luminal subtype was a significant predictor for local recurrence (P < 0.001). On multivariate analysis, a non-luminal subtype remained as an independent predictor for local recurrence (P = 0.003, odds ratio: 10.9, 95% confidence interval: 2.23–53.1). In conclusion, PMRT without usage of a bolus resulted in a low rate of severe acute dermatitis without an apparent increase in local recurrence. PMRT without usage of a bolus may be reasonable, especially for patients with a luminal subtype.

Clinical Advantage of Chest-wall Post-mastectomy Radiation Therapy Without Bolus

“…In this study, only 4% of patients had local recurrences and 10% developed grade 2 acute radiation dermatitis, and these results were similar to those of Nakamura et al (6) who found that after PMRT without bolus, 11% of patients had locoregional recurrence and 9% developed grade 2 acute radiation dermatitis.…”

Quantitative Effect of Bolus on Skin Dose in Postmastectomy Radiation Therapy

“…Based on the lack of evidence-based causation between changes in dose and potential recurrence, there is variability of bolus application in a clinical setting. Some physicians may not find that the benefits of the bolus outweigh the associated risks, namely the increased risk of RD [6,14,17,18]. Skin toxicity is an exceedingly common side effect of RT which can be very painful, may lead to long-term sequelae such as undesirable cosmesis, fibrosis, chronic pain, hyperpigmentation, and telangiectasia, and can decrease quality of life.…”

“…Owing to higher recurrence rates in tumours with skin involvement, it is important to ensure the skin is being adequately dosed. However, some literature suggests that differences in skin dose may not influence rates of locoregional recurrence [6,15,17,18,20]. Despite these findings, bolus is still widely used and it should be noted that most published data on this topic comes from small case-control studies retrospectively comparing separate groups of patients [6,14,15].…”

“…Thus, these patients present with clinical factors associated with higher risks of recurrence. Furthermore, some studies only assessed PMRT without bolus and had no comparison with bolus usage [17,18]. One study by Yap et al compared their results in treatment without bolus with previous literature.…”

In search of a one plan solution for VMAT post‐mastectomy chest wall irradiation

“…Regardless of planning technique, to date, there has been a lack of consensus on whether the routine use of bolus in post-mastectomy radiation therapy is necessary or not. 9,10 The guidelines of the American Society of Clinical Oncology first published in 2001 11 and later updated in 2016 12 stated that "whether it is necessary to apply the bolus every day, less frequently, or at all is uncertain." As such, whether bolus is used routinely or not, its thickness and frequency are often decided by clinical experience and vary from center to center.…”