Accelerated hypo-fractionated Whole Breast Radiotherapy by 3-Dimensional conformal field-in-field approach for simultaneous integration of boost: do we have an optimal planning solution that fits most?

Abstract

Background: Compliance to Whole Breast(WB) Radiotherapy(RT) may be improved by shortening treatment duration using accelerated hypofractionated schedules. The current study evaluates clinical feasibility of hypofractionated WBRT with Simultaneous Integrated Boost (SIB) by 3Dimensional Conformal Radiotherapy(3DCRT) Field-in-Field (FIF) technique in terms of dosimetric acceptability, acute toxicities and cosmesis at 6 months. Materials and Methods: Female patients with early breast cancer were recruited post breast conserving surgery. WBRT was planned using 3DCRT -FIF technique with static multi-leaf collimators and 6 MegaVoltage(MV) photons. 40 Gray(Gy)/15 fractions at 2.67 Gy/fraction with SIB to tumor bed of 48Gy in 15 fractions at 3.2 Gy/fraction was delivered. Acute skin toxicity was and cosmesis were documented. Results: Mean age of patients was 48 + 2 years. 5/11 patients with right and 6/11 with left breast cancer. Mean Planning Target Volume (PTV)-WB V38(95%) = 94.98 + 3.92 %. Dmax = 51.04 + 0.99Gy (106%) was confined within boost volume. No isolated hot spots > 48 Gy were found in the breast outside boost volume. Conformity Index(CI) was 1.31+ 0.2, within the acceptable range of >0.95 and < 2.0. PTV-boost 45.6Gy(95%) = 98.34% + 1.79%. Dose to Organs at Risk were within the acceptable limits. Assessment by Harvard Breast cosmesis criteria revealed grade 2 score for all patients except one patient whose score consistently remained grade 3 after surgery. Conclusion: WBRT with SIB by 3DCRT-FIF allows us to achieve acceptable dosimetric parameters, good cosmetic outcome and good patient compliance. This may be adapted in centres which lack advanced radiation facilities. 

Key words: Whole Breast Radiotherapy, 3DCRT, Field-in-Field, Simultaneous Integrated Boost