Partial breast irradiation

The RAPID trial (NCT00282035) randomly assigned 2,135 women aged 40 years or older with ductal carcinoma in situ or node-negative breast cancer treated by breast-conserving surgery to receive either external-beam accelerated partial breast irradiation (APBI) (38.5 Gy in ten fractions delivered twice per day over 5–8 days) or whole-breast radiation therapy (42.5 Gy in 16 fractions delivered once per day over 21 days, or 50 Gy in 25 fractions once per day over 35 days).[15] Sixty-five ipsilateral breast tumor recurrences were observed, 37 in the APBI group, and 28 in the whole-breast irradiation group.

The RAPID trial (NCT00282035) randomly assigned 2,135 women aged 40 years or older with ductal carcinoma in situ or node-negative breast cancer treated by breast-conserving surgery to receive either external-beam accelerated partial breast irradiation (APBI) (38.5 Gy in ten fractions delivered twice per day over 5–8 days) or whole-breast radiation therapy (42.5 Gy in 16 fractions delivered once per day over 21 days, or 50 Gy in 25 fractions once per day over 35 days).[15] Sixty-five ipsilateral breast tumor recurrences were observed, 37 in the APBI group, and 28 in the whole-breast irradiation group.

In patients treated with APBI, the 5-year cumulative rate of ipsilateral breast tumor recurrence was 2.3% (95% CI, 1.4%–3.2%) and the 8-year cumulative rate was 3.0% (95% CI, 1.9%–4.0%).

The RAPID trial (NCT00282035) randomly assigned 2,135 women aged 40 years or older with ductal carcinoma in situ or node-negative breast cancer treated by breast-conserving surgery to receive either external-beam accelerated partial breast irradiation (APBI) (38.5 Gy in ten fractions delivered twice per day over 5–8 days) or whole-breast radiation therapy (42.5 Gy in 16 fractions delivered once per day over 21 days, or 50 Gy in 25 fractions once per day over 35 days).[15] Sixty-five ipsilateral breast tumor recurrences were observed, 37 in the APBI group, and 28 in the whole-breast irradiation group.

In patients treated with whole-breast radiation therapy, the 5-year cumulative rate of ipsilateral breast tumor recurrence was 1.7% (range, 0.9%–2.5%) and the 8-year cumulative rate was 2.8% (range, 1.8%–3.9%).

The RAPID trial (NCT00282035) randomly assigned 2,135 women aged 40 years or older with ductal carcinoma in situ or node-negative breast cancer treated by breast-conserving surgery to receive either external-beam accelerated partial breast irradiation (APBI) (38.5 Gy in ten fractions delivered twice per day over 5–8 days) or whole-breast radiation therapy (42.5 Gy in 16 fractions delivered once per day over 21 days, or 50 Gy in 25 fractions once per day over 35 days).[15] Sixty-five ipsilateral breast tumor recurrences were observed, 37 in the APBI group, and 28 in the whole-breast irradiation group.

The hazard ratio (HR) for APBI versus whole-breast radiation therapy was 1.27 (90% CI, 0.84–1.91).

The RAPID trial (NCT00282035) randomly assigned 2,135 women aged 40 years or older with ductal carcinoma in situ or node-negative breast cancer treated by breast-conserving surgery to receive either external-beam accelerated partial breast irradiation (APBI) (38.5 Gy in ten fractions delivered twice per day over 5–8 days) or whole-breast radiation therapy (42.5 Gy in 16 fractions delivered once per day over 21 days, or 50 Gy in 25 fractions once per day over 35 days).[15] Sixty-five ipsilateral breast tumor recurrences were observed, 37 in the APBI group, and 28 in the whole-breast irradiation group.

Thus, the upper bound of the estimated 90% CI did not exceed the noninferiority margin of 2.02. The APBI arm was associated with less short-term but more long-term toxicity.[15][Level of evidence B1]

The NSABP B-39/RTOG 0413 trial (NCT00103181) randomly assigned 4,216 women to whole-breast radiation therapy or APBI.[16] Whole-breast radiation therapy was delivered in 25 daily fractions of 50 Gy over 5 weeks, with or without a supplemental boost to the tumor bed, and APBI was delivered as 34 Gy of brachytherapy or 38.5 Gy of external-bream radiation therapy in 10 fractions, over 5 treatment days within an 8-day period.

The NSABP B-39/RTOG 0413 trial (NCT00103181) randomly assigned 4,216 women to whole-breast radiation therapy or APBI.[16] Whole-breast radiation therapy was delivered in 25 daily fractions of 50 Gy over 5 weeks, with or without a supplemental boost to the tumor bed, and APBI was delivered as 34 Gy of brachytherapy or 38.5 Gy of external-bream radiation therapy in 10 fractions, over 5 treatment days within an 8-day period.

At a median follow-up of 10.2 years (interquartile range, 7.5–11.5), 90 of 2,089 women (4%) eligible for the primary outcome in the APBI group and 71 of 2,036 women (3%) in the whole-breast radiation therapy group had an ipsilateral breast tumor recurrence (HR, 1.22; 90% CI, 0.94–1.58). The results did not meet the prespecified criterion for equivalence, an HR of 1.50 or less.

The NSABP B-39/RTOG 0413 trial (NCT00103181) randomly assigned 4,216 women to whole-breast radiation therapy or APBI.[16] Whole-breast radiation therapy was delivered in 25 daily fractions of 50 Gy over 5 weeks, with or without a supplemental boost to the tumor bed, and APBI was delivered as 34 Gy of brachytherapy or 38.5 Gy of external-bream radiation therapy in 10 fractions, over 5 treatment days within an 8-day period.

Toxicity was not substantially different between the arms.[16][Level of evidence B1]

The randomized, phase III, single-center APBI-IMRT-Florence trial (NCT02104895) evaluated differences in ipsilateral breast tumor recurrence (IBTR) among patients who received APBI using either intensity-modulated radiation therapy, an advanced radiation technique, (30 Gy in five once-daily fractions) or whole-breast radiation therapy with tangents (50 Gy in 25 fractions with a tumor bed boost). Patients had previously undergone breast-conserving surgery. A total of 520 patients were randomly assigned (whole-breast radiation therapy, n = 260; APBI, n = 260).[17]

The randomized, phase III, single-center APBI-IMRT-Florence trial (NCT02104895) evaluated differences in ipsilateral breast tumor recurrence (IBTR) among patients who received APBI using either intensity-modulated radiation therapy, an advanced radiation technique, (30 Gy in five once-daily fractions) or whole-breast radiation therapy with tangents (50 Gy in 25 fractions with a tumor bed boost). Patients had previously undergone breast-conserving surgery. A total of 520 patients were randomly assigned (whole-breast radiation therapy, n = 260; APBI, n = 260).[17]

The 10-year cumulative incidence of IBTR was 2.5% in the whole-breast radiation therapy arm and 3.7% in the APBI arm (HR, 1.56; 95% CI, 0.55–4.37; P = .40).

The randomized, phase III, single-center APBI-IMRT-Florence trial (NCT02104895) evaluated differences in ipsilateral breast tumor recurrence (IBTR) among patients who received APBI using either intensity-modulated radiation therapy, an advanced radiation technique, (30 Gy in five once-daily fractions) or whole-breast radiation therapy with tangents (50 Gy in 25 fractions with a tumor bed boost). Patients had previously undergone breast-conserving surgery. A total of 520 patients were randomly assigned (whole-breast radiation therapy, n = 260; APBI, n = 260).[17]

The 10-year OS rate was 91.9% in both arms (HR, 0.95; 95% CI, 0.50–1.79; P = .86). Breast cancer–specific survival at 10 years was 96.7% in the whole-breast radiation therapy arm and 97.8% in the APBI arm (HR, 0.65; 95% CI, 0.21–1.99; P = .45).

The randomized, phase III, single-center APBI-IMRT-Florence trial (NCT02104895) evaluated differences in ipsilateral breast tumor recurrence (IBTR) among patients who received APBI using either intensity-modulated radiation therapy, an advanced radiation technique, (30 Gy in five once-daily fractions) or whole-breast radiation therapy with tangents (50 Gy in 25 fractions with a tumor bed boost). Patients had previously undergone breast-conserving surgery. A total of 520 patients were randomly assigned (whole-breast radiation therapy, n = 260; APBI, n = 260).[17]

There were fewer acute and late toxicities in the APBI arm (P = .0001 for both comparisons). The APBI arm had improved cosmetic outcomes as evaluated by both physicians and patients (P = .0001 for both comparisons).