Partial breast radiotherapy with simple teletherapy techniques.

A prospective pilot study of partial breast irradiation (PBI) with conventional vs hypofractionated schedules was set out. The study aimed to determine efficacy, acute and late side effects, and the preference of photon vs electron irradiation based on individual features. Patients were enrolled according to internationally accepted guidelines on PBI. Conformal radiotherapy plans were generated with both photon and electron beams, and the preferred technique based on dose homogeneity and the radiation exposure of healthy tissues was applied. For electron dose verification, a special phantom was constructed. Patients were randomized for fractionation schedules of 25 × 2 vs 13 × 3Gy. Skin and breast changes were registered at the time of and ≥1 year after the completion of radiotherapy. Dose homogeneity was better with photons. If the tumor bed was located in the inner quadrants, electron beam gave superior results regarding conformity and sparing of organ at risk (OAR). If the tumor was situated in the lateral quadrants, conformity was better with photons. A depth of the tumor bed ≥3.0cm predicted the superiority of photon irradiation (odds ratio [OR] = 23.6, 95% CI: 5.2 to 107.5, p < 0.001) with >90% sensitivity and specificity. After a median follow-up of 39 months, among 72 irradiated cases, 1 local relapse out of the tumor bed was detected. Acute radiodermatitis of grade I to II, hyperpigmentation, and telangiectasia developed ≥1 year after radiotherapy, exclusively after electron beam radiotherapy. The choice of electrons or photons for PBI should be based on tumor bed location; the used methods are efficient and feasible.

Radiation dose to the nodal regions during prone versus supine breast irradiation.

BACKGROUND: Prone positioning for breast radiotherapy is preferable when the aim is a reduction of the dose to the ipsilateral lung or the heart in certain left-sided cases. MATERIALS AND METHODS: In 100 breast cancer cases awaiting postoperative whole-breast radiotherapy, conformal radiotherapy plans were prospectively generated in both prone and supine positions. The axillary nodal region (levels I-III) and internal mammary (IM) lymph-node region in the upper three intercostal spaces were retrospectively contoured. The mean doses to the nodal regions and the volume receiving 25 Gy (V25Gy), V45Gy, and V47.5Gy were compared between the two treatment positions. RESULTS: In most cases, the doses to axillary levels I-III and the IM lymph nodes were inadequate, regardless of the treatment position. The nodal doses were significantly lower in the prone than in the supine position. The radiation doses to levels II-III and IM nodes were especially low. The V45Gy and V47.5Gy of the level I axillary lymph nodes were 54.6% and 40.2%, respectively, in the supine, and 3.0% and 1.7%, respectively, in the prone position. In the supine position, only 17 patients (17%) received a mean dose of 45 Gy to the axillary level I nodes. CONCLUSION: The radiation dose to the axillary and IM lymph nodes during breast radiotherapy is therapeutically insufficient in most cases, and is significantly lower in the prone position than in the supine position.