B. McCormick

Intensity-modulated tangential beam irradiation of the intact breast

PURPOSEnTo evaluate the potential benefits of intensity modulated tangential beams in the irradiation of the intact breast.nnnMETHODS AND MATERIALSnThree-dimensional treatment planning was performed on five left and five right breasts using standard wedged and intensity modulated (IM) tangential beams. Optimal beam parameters were chosen using beams-eye-view display. For the standard plans, the optimal wedge angles were chosen based on dose distributions in the central plane calculated without inhomogeneity corrections, according to our standard protocol. Intensity-modulated plans were generated using an inverse planning algorithm and a standard set of target and critical structure optimization criteria. Plans were compared using multiple dose distributions and dose volume histograms for the planning target volume (PTV), ipsilateral lung, coronary arteries, and contralateral breast.nnnRESULTSnSignificant improvements in the doses to critical structures were achieved using intensity modulation. Compared with a standard-wedged plan prescribed to 46 Gy, the dose from the IM plan encompassing 20% of the coronary artery region decreased by 25% (from 36 to 27 Gy) for patients treated to the left breast; the mean dose to the contralateral breast decreased by 42% (from 1.2 to 0.7 Gy); the ipsilateral lung volume receiving more than 46 Gy decreased by 30% (from 10% to 7%); the volume of surrounding soft tissue receiving more than 46 Gy decreased by 31% (from 48% to 33%). Dose homogeneity within the target volume improved greatest in the superior and inferior regions of the breast (approximately 8%), although some decrease in the medial and lateral high-dose regions (approximately 4%) was also observed.nnnCONCLUSIONnIntensity modulation with a standard tangential beam arrangement significantly reduces the dose to the coronary arteries, ipsilateral lung, contralateral breast, and surrounding soft tissues. Improvements in dose homogeneity throughout the target volume can also be achieved, particularly in the superior and inferior regions of the breast. It remains to be seen whether the dosimetric improvements achievable with IMRT will lead to significant clinical outcome improvements.

Unilateral postoperative chest wall radiotherapy in bilateral tissue expander/ implant reconstruction patients : A prospective outcomes analysis

Background: Implant reconstruction has a major role to play in breast reconstruction, as some patients neither wish nor are suitable for autogenous reconstruction. The suitability of implant reconstruction in patients who may receive postoperative, adjuvant radiation therapy has not, however, been fully clarified. The purpose of this study was to evaluate complications, capsular contracture, aesthetic outcomes, and patient satisfaction in patients who have undergone bilateral tissue expander/implant reconstruction and unilateral, post exchange, adjuvant radiotherapy. In this study population, the effect of radiation can best be appreciated because the nonirradiated breast acts as a control. Methods: A review of all bilateral tissue expander/implant reconstructions at a single cancer center was undertaken. Twelve patients who underwent bilateral expander/implant reconstruction and unilateral postexchange radiotherapy were eligible for participation. A prospective evaluation of complications, cosmesis, and patient satisfaction was performed. The evaluation of cosmesis and patient satisfaction was executed for 10 of the 12 patients, as two were dead at the time of follow-up. Results: Mean follow-up was 23.5 months (range, 12 to 58.5 years). In 40 percent of patients, there was no discernible difference in capsular contracture between the irradiated and nonirradiated breasts. In 50 percent of patients, the irradiated breast demonstrated increased contracture by a single modified Baker grade. In 10 percent of patients, contracture of the irradiated breast was two modified Baker grades greater than that of the nonirradiated side (grade III versus grade I). Conclusion: For the majority of patients, the degree of capsular contracture was higher on the irradiated side, yet overall symmetry, aesthetic results, and patient satisfaction remained high. These data support the conclusion that immediate, bilateral breast reconstruction using tissue expansion and implants is an acceptable option for the subset of patients who may undergo unilateral, postexchange radiotherapy.

Study of quadrant high-dose intraoperative radiation therapy for early-stage breast cancer

Partial breast irradiation has been tested in limited pilot studies and shown to provide acceptable cosmesis, minimal toxicity and adequate local control. The aim of this study was to determine the feasibility of using quadrant high‐dose intraoperative radiation therapy (IORT) for the treatment of early‐stage breast cancer.

The use of lymphoscintigraphy in treatment planning of primary breast cancer

A technique is described for the use of lymphoscintigraphy in treatment planning of primary breast patients. During simulation of the treatment fields, the positions of the internal mammary nodes are projected back toward the source onto the patient skin surface and are marked by radio-opaque markers for visualization on films. Exact solutions for the coordinates of these surface projection points are derived. Approximate solutions are also given which are independent of the isocenter location and primarily dependent on the treatment field gantry angle. If a typical couch angle and field size are assumed, the projection points can be calculated for various gantry angles prior to simulation. Generally, a decision can then be made beforehand whether it would be better to use deep tangents or a separate field to treat the internal mammary nodes. During simulation, the surface projection points serve as visual and fluoroscopic guides to field design and optimization. A method is also presented for projecting the internal mammary node positions onto a single transverse patient contour for conventional 2-dimensional treatment planning. By accurately showing the projected location of the node with respect to the field edge, adequate treatment margin can be assured.

Applicator for optimum cobalt-60 primary breast treatments

A breast applicator has been designed to optimize 3 field breast treatments for 60Co. The device has a six half value layer beam splitting block constructed in two sections. The larger permanently mounted section is sufficient for treating 90% of the patients. Slots are available for mounting cerroband blocks, and any of five brass half field wedges. A magnetically attached front and back-pointer assembly readily breaks away in the event of a collision between pointer and patient. With this design the breast applicator with wedges and blocks has in-field surface doses reduced to that of an open field without accessory devices. The 50-90% dose decrement of the radiation penumbra for the half field block is comparable to that for the field edge of a typical 6 MV X ray unit, although the 50-10% decrement is larger. The average out-of-field dose at the surface is 8% and is 5% at the depth of dose maximum. The combination for this applicator of sharp penumbra and low out-of-field dose leads to reduced lung and opposite breast doses. The latter was confirmed with TLD measurements on 10 patients, and yielded an average opposite breast dose of 230 cGy for a 4600 cGy prescription. Thus, half-field blocking devices do not preclude, as has been stated in the literature, acceptable opposite breast doses. In addition, proper design of these devices can significantly improve the radiation characteristics for primary breast treatments.

Irradiation after immediate tissue expander/implant breast reconstruction: Outcomes, complications, aesthetic results, and satisfaction among 156 patients

Chest wall irradiation is becoming increasingly common for mastectomy patients who have opted for immediate breast reconstruction with tissue expanders and implants. The optimal approach for such patients has not yet been defined. This study assesses the outcomes of a reconstruction protocol for patients who require irradiation after tissue expander/implant reconstruction. The charts of all patients who underwent immediate tissue expander/implant reconstruction at Memorial Sloan-Kettering Cancer Center between January of 1995 and June of 2001 and who had not previously undergone irradiation were retrospectively reviewed. A subgroup of patients who required chest wall irradiation after mastectomy and reconstruction was identified. Those patients were treated according to the following treatment algorithm: (1) reconstruction with tissue expander placement at the time of mastectomy , (2) tissue expansion during postoperative chemotherapy, (3) exchange of the tissue expander for a permanent implant approximately 4 weeks after the completion of chemotherapy, and (4) chest wall irradiation beginning 4 weeks after the exchange. All irradiated patients with at least 1 year of follow-up monitoring after the completion of radiotherapy were evaluated with respect to aesthetic outcomes, capsular contracture, and patient satisfaction. A control group of nonirradiated patients was randomly selected from the cohort of patients treated during the study period. During the 5-year study period, a total of 687 patients underwent immediate reconstruction with tissue expanders. Eighty-one patients underwent postoperative irradiation after placement of the final implant. A total of 68 patients who received postoperative chest wall irradiation underwent at least 1 year of follow-up monitoring after the completion of radiotherapy, with a mean follow-up period of 34 months. Seventy-five nonirradiated patients were evaluated as a control group. Overall, 68 percent of the irradiated patients developed capsular contracture, compared with 40 percent in the nonirradiated group (p = 0.025). Eighty percent of the irradiated patients demonstrated acceptable (good to excellent) aesthetic results, compared with 88 percent in the nonirradiated group (p = not significant). Sixty-seven percent of the irradiated patients were satisfied with their reconstructions, compared with 88 percent of the nonirradiated patients (p = 0.004). Seventy-two percent of the irradiated patients stated that they would choose the same form of reconstruction again, compared with 85 percent of the nonirradiated patients. The results of this study suggest that tissue expander/implant reconstruction is an acceptable surgical option even when followed by postoperative radiotherapy and should be considered in the reconstruction algorithm for all patients, particularly those who may not be candidates for autogenous reconstruction.