Abstract 1089
Background
Hypofractionation (2.67 Gy/#/day) enables the delivery of larger dose of radiation per treatment fraction thereby completing the treatment over shorter duration compared to conventional fractionation (2Gy/#/day), reduced cost of treatment and increased convenience to patients. It also provides with distinct radiobiological advantage as breast tissue has a relatively low α/β ratio of 4.
Methods
Twenty five patients of carcinoma of left breast were accrued from August 2015 to December 2016. The patients underwent radiotherapy simulation. Each patient underwent conventional 2D and 3DCRT planning to prescribed dose of 40 Gy/15# on MONACO treatment planning system after delineation of target volume (planning target volume - PTV), and organs at risk (heart & lung). The aim was to cover 95% of planning target volume (PTV) with at least 95% of prescribed dose keeping the global maximum <107% and cold <2%. The dose constraints to the heart was V25<10%, mean lung dose <10Gy, V5<40%, V20<30% & V30<20%.
Results
We observed that there was statistically significant difference in mean dose & V25 (volume receiving 25Gy) of heart as well as mean dose, V5(volume receiving 5 Gy), V20 (volume receiving 20 Gy) & V30 (volume receiving 30Gy) of lung. The global maximum was also lesser in 3DCRT plans which was statistically significant.Table: 32P
| 2D (Gy) | 3DCRT (Gy) | P value | |
|---|---|---|---|
| HEART | |||
| Mean | 9.4 | 4.9 | <0.01 |
| V25 | 16.9 | 4.9 | <0.001 |
| LUNG | |||
| Mean | 9.7 | 7 | <0.01 |
| V5 | 31.6 | 26 | <0.01 |
| V20 | 21.3 | 14.8 | <0.01 |
| V30 | 17.6 | 10.4 | <0.001 |
| PTV (95%) | 38.6 | 38.5 | 0.7 |
| GLOBAL MAXIMUM | 46.8 | 42.9 | <0.001 |
Conclusions
3DCRT is strongly recommended in hypofractionation of whole breast for better sparing of lungs and heart in addition to reducing the global maximum dose delivered to the breast.
Editorial acknowledgement
Clinical trial identification
Legal entity responsible for the study
Dr Mukul Roy.
Funding
Has not received any funding.
Disclosure
All authors have declared no conflicts of interest.