Whole-breast irradiation: a subgroup analysis of criteria to stratify for prone position treatment.

To select among breast cancer patients and according to breast volume size those who may benefit from 3D conformal radiotherapy after conservative surgery applied with prone-position technique. Thirty-eight patients with early-stage breast cancer were grouped according to the target volume (TV) measured in the supine position: small (≤400 mL), medium (400-700 mL), and large (≥700 ml). An ad-hoc designed and built device was used for prone set-up to displace the contralateral breast away from the tangential field borders. All patients underwent treatment planning computed tomography in both the supine and prone positions. Dosimetric data to explore dose distribution and volume of normal tissue irradiated were calculated for each patient in both positions. Homogeneity index, hot spot areas, the maximum dose, and the lung constraints were significantly reduced in the prone position (p < 0.05). The maximum heart distance and the V(5Gy) did not vary consistently in the 2 positions (p = 0.06 and p = 0.7, respectively). The number of necessary monitor units was significantly higher in the supine position (312 vs. 232, p < 0.0001). The subgroups analysis pointed out the advantage in lung sparing in all TV groups (small, medium and large) for all the evaluated dosimetric constraints (central lung distance, maximum lung distance, and V(5Gy), p < 0.0001). In the small TV group, a dose reduction in nontarget areas of 22% in the prone position was detected (p = 0.056); in the medium and high TV groups, the difference was of about -10% (p = NS). The decrease in hot spot areas in nontarget tissues was 73%, 47%, and 80% for small, medium, and large TVs in the prone position, respectively. Although prone breast radiotherapy is normally proposed in patients with breasts of large dimensions, this study gives evidence of dosimetric benefit in all patient subgroups irrespective of breast volume size.

Sentinel lymph node biopsy in women with pT1a or "microinvasive" breast cancer.

The role of sentinel lymph node biopsy (SLNB) in pT1a and "microinvasive" breast cancer has not been extensively studied. We report our experience with SLNB in patients with "minimal" breast cancer to determine the incidence and type of SLN metastases, and to study the potential impact on their surgical or oncological management. Among some 3387 women operated upon for primary breast cancer who underwent sentinel lymph node biopsy at nine institutions participating in the Rome Breast Cancer Study Group, 251 were staged pT1a or pT1mic (7.4%). There were 13 cases of sentinel lymph node metastases identified in this group of patients (5.2%), seven macrometastases and six micrometastases. Additionally, ITC were diagnosed by immunohistochemistry in four cases (1.6%). The incidence of SLN metastases was 7/174 (4%) and 6/77 (7.8%) in patients with pT1a and pT1mic tumors, respectively (p=0.2). Age and histological grade were predictive factors for SLN metastases. Chemotherapy was seldom directed by axillary node status (8/38 patients). As the incidence of SLN metastases in these patients is very small, particularly in the pT1a group, the indications for even a minimally invasive procedure, such as sentinel lymph node biopsy, should be probably individualized.