Radiotherapy to the Left Breast with 3DCRT, IMRT or VMAT: International Medical Center Experience

Radiation therapy after conservative breast surgery is an integral part of the treatment of early breast cancer. The aim of radiotherapy is to achieve the best coverage of the Planning Target Volume (PTV), while reducing the dose to the Organs at Risk (OAR). Such goals are not always achievable with the conformal three dimensions plans (3DCRT). Recently, radiation oncologist uses Intensity Modulated Radiotherapy (IMRT) and Volumetric Modulated Arc Therapy (VMAT) for irradiating the breast. In this study, we compared 3DCRT, IMRT and VMAT for left breast cancer patients in terms of PTV coverage, OAR. We also revised the different dose distribution in 1) different breast volume categories, 2) nodal irradiation versus breast only, and 3) boost versus no boost. Results: The routinely reported dose constrains for the ipsilateral lung and for the heart were not significantly different on comparing the three techniques. While for the contralateral lung, the difference in mean dose was in favor of 3DCRT. In large breast volume, 3DCRT provided a lower Max dose to the contralateral lung and the lowest mean dose to the contralateral breast when compared to IMRT p < 0. 046. In case of no nodal irradiation, the contralateral breast mean dose was lower in 3DCRT in comparison to IMRT and VMAT p < 0.037. When boost dose was given, 3DCRT plans had produced a lower Max dose to the contralateral lung p < 0.017. Conclusion: The three techniques (3DCRT, IMRT, and VMAT) can meet the clinical dosimetry demands of radiotherapy for left breast cancer after conservative surgery, as long as the routinely OARs only (heart and ipsilateral lung) are reported. Our study showed that 3CDRT can provide a lower dose to the contralateral organs (breast and lung), specially, in case of large breast volumes, no nodal irradiation and when a boost is given.

Improved local control without elective nodal radiotherapy in patients with unresectable NSCLC treated by 3D-CRT

To investigate the influence of prophylactic elec-tive nodal irradiation on the therapeutic results of definitive radiotherapy for patients with stage IIIA or stage IIIB unre-sectable non-small-cell lung cancer,55 patients with clini-cally inoperable advanced non-small-cell lung cancer were studied.After four cycles of induction chemotherapy,the patients were divided into two groups at random.In one group,the elective nodal irradiation was included in clinical tumor volume(CTV)of definitive radiotherapy(ENI group);and in the other group,elective nodal irradiation was not included in CTV(non-ENI group).For the patients in the ENI group,the mean prescription dose for gross tumor volumes was 58.4 Gy,while for the patients in the non-ENI group,it was 65.8 Gy(P<0.05).The responsive rates were 45.8%and 74.0%(P<0.05),and the rate of the elective nodal failure(ENF)was 4.2%and 11.1%,respectively.Kaplan-Meier analysis showed that the mean local-progression-free survival time was 11.0 and 15.0 months,and one-year local-failure rates were 51.9%and 24.5%(P<0.05).The median overall survival time was 13.0 and 15.0 months,respectively(P=0.084).The one-year survival rates were 55.7%and 72.5%,and two-year survival rates were 0%and 19.9%.There was no significant difference in the occurrences of radiation-associated complications between the two groups.Our results showed that omitting elective nodal irradiation did not result in a high incidence of elective nodal failure.On the contrary,it decreased local failure by increasing prescrip-tion doses to the primary diseases and lymphadenopaphy,and thereby it may further prolong the patients’survival.