Comparison of Treatment Outcome Between Invasive Lobular and Ductal Carcinomas in Patients Receiving Partial Breast Irradiation With Intraoperative Electrons.

PURPOSE: To investigate the local outcome of patients after accelerated partial breast irradiation with intraoperative electrons (IORT) for invasive lobular carcinoma (ILC) compared with invasive ductal carcinoma (IDC). METHODS AND MATERIALS: From 1999 to 2007, 2173 patients were treated with breast-conserving surgery and IORT (21 Gy/1 fraction) as the sole local treatment: 252 patients with ILC (11.6%) were compared with 1921 patients with IDC in terms of local control. RESULTS: Compared with the IDC subgroup, patients with ILC had a low-risk profile and were more hormone responsive. The 5- and 10-year in-breast tumor reappearance (IBTR) rates were 5.5% and 14.4%, respectively, for the IDC group and 7.5% and 21.8%, respectively, for the ILC group (log-rank P=.03). The excess risk of IBTR associated with ILC was particularly high for small tumors (≤1 cm: hazard ratio [HR], 2.24; 95% confidence interval [CI], 1.03-4.85), elderly patients (60-69 years: HR, 2.27; 95% CI, 1.11-4.63; ≥70 years: HR, 3.28; 95% CI, 1.08-10.0), low-grade tumors (grade 1: HR, 3.50; 95% CI, 1.05-11.7), and luminal A molecular subtype (HR, 3.18; 95% CI, 1.49-6.77). Among the ILC histologic variants, no difference between classic and nonclassic subgroups was observed, although the signet ring cell and solid variants had the worst local control. CONCLUSIONS: Despite a favorable tumor profile, accelerated partial breast irradiation with IORT led to a higher incidence of IBTRs in patients with ILC compared with those with IDC. Our institutional experience emphasized the importance of the size of the irradiation field, pointing to the use of larger collimators, even when dealing with small tumors, to improve local control.

Contouring of the Pharyngeal Superior Constrictor Muscle (PSCM). A cooperative study of the Italian Association of Radiation Oncology (AIRO) Head and Neck Group.

BACKGROUND AND PURPOSE: Irradiation of the Pharyngeal Superior Constrictor Muscle (PSCM) seems to play a crucial role in radiation-related swallowing dysfunctions. Purpose of our study was to quantify operator-related variability in the contouring of PSCM on Computed Tomography (CT) scans and adherence with contours derived from MR images. MATERIALS AND METHODS: Three sets of treatment planning CT and their corresponding MR images were selected. Contouring of the PSCM was performed using both a literature-based method, derived from literature review, and an optimized method, derived from Magnetic Resonance (MR) images thus obtaining "literature-based" and "optimized" contours. Each operator contoured the PSCM on CT scans according to both methods for three times in three different days. Inter- and intra-operator variability and adherence to a contour obtained from MR images (named "MR-derived" contour) were analyzed. RESULTS: Thirty-four operators participated and 612 contours were obtained. Both intra- and inter-operator variability and adherence to the "MR-derived" contour were significantly different between the two methods (p⩽0.05). The "optimized" method showed a lower intra- and inter-operator variability and a higher adherence to the "MR-derived" contour. CONCLUSIONS: The "optimized" method ameliorates both operator-related variability and adherence with MR images.