Accelerated partial breast irradiation using once-daily fractionation: analysis of 312 cases with four years median follow-up

Abstract

BackgroundThere are limited data on accelerated partial breast irradiation (APBI) using external beam techniques. Moreover, there are recent reports of increased fibrosis and unacceptable cosmesis with APBI using external beam with BID fractionation. We adopted a once daily regimen of APBI with fractionation similar to that shown to be effective in a Canadian randomized trial of whole breast irradiation. It is unclear whether patients with DCIS or invasive lobular carcinoma (ILC) are suitable for APBI.MethodsThe retrospective cohort included 310 patients with 312 tumors of T1-T2N0-N1micM0 invasive ductal carcinoma (IDC), ILC, or Tis (DCIS) treated with APBI via external beam. Most patients were treated using IMRT with 16 daily fractions of 270 cGy to a dose of 4320 cGy. The target volume included the lumpectomy cavity plus 1.0 cm to account for microscopic disease and an additional 0.5 to 1.0 cm for setup uncertainty and breathing motion. Ipsilateral breast failure (IBF) was pathologically confirmed as a local failure (LF) or an elsewhere failure (EF).ResultsMedian follow-up was 49 months. Among the 312 cases, 213 were IDC, 31 ILC, and 68 DCIS. Median tumor size was 1.0 cm. There were 9 IBFs (2.9%) including 5 LFs and 4 EFs. The IBF rates among patients with IDC, ILC, and DCIS were 2.4%, 3.2%, and 4.4%, respectively, with no significant difference between histologies. When patients were analyzed by the ASTRO APBI consensus statement risk groups, 32% of treated cases were considered suitable, 50% cautionary, and 18% unsuitable. The IBF rates among suitable, cautionary, and unsuitable patients were 4.0%, 2.6%, and 1.8%, respectively, with no significant difference between risk groups. Acute skin reactions were rare and long-term cosmetic outcome was very good to excellent.ConclusionsExternal beam APBI with once daily fractionation has a low rate of IBF consistent with other published APBI studies. The ASTRO risk stratification did not differentiate a subset of patients with a higher rate of IBF. APBI may be an appropriate treatment for women with DCIS and ILC.

Long-Term Outcomes of Once-Daily Accelerated Partial-Breast Irradiation With Tomotherapy: Results of a Phase 2 Trial

“…These are similar or lower than several once-daily APBI series with 5year outcomes. [22][23][24][25] Shaiky et al, 26 with a median followup of 49 months, obtained IBTR of 1.9% and 1.0% of axillary failure. Goyal et al, 27 although only on 45 patients treated with once-daily APBI with 3D conformal radiation therapy technique, observed an IBTR of 0% at 3 years.…”

Increased Risk for Ipsilateral Breast Tumor Recurrence in Invasive Lobular Carcinoma after Accelerated Partial Breast Irradiation Brachytherapy

“…However, it should be noted that all four patients with ILC who developed IBTR underwent preoperative MRI. Whereas some studies have shown a higher risk of IBTR for ILC [25, 29], other studies have failed to identify ILC as a significant predictor of IBTR after APBI [26, 30, 31]. The prospective experience with ILC is limited, as the histology accounts for less than 10% of the study population in select trials [10, 11], whereas others have excluded ILC cases altogether [6, 8, 15].…”

Brachytherapy is better than external beam therapy for partial breast irradiation

“…Our own five-year follow-up experience at New York University, shows a 1% recurrence rate with 11% fair-to-poor cosmesis, 10 which is in line with many studies. 14,15 My opponent pointed out that the lack of defined prescription standards can result in large high dose regions which affect cosmesis. 4 This is the exact type of issue that is currently being studied and will eventually be solved.…”