Abstract 264P
Background
The standard treatment of locally advanced rectal cancer (RC) (stage II and III) has been the long-cycle chemoradiotherapy (CRT) with 5-FU/Capecitabine with preoperative RT 45-50.4 Gy in 25-28 fractions, having demonstrated in several randomized clinical trials improvements in local recurrence (LR) rates, sphincter-sparing surgery and treatment-related toxicity with preoperative therapy. Short-cycle radiotherapy (SCRT) 25 Gy in 5 days in a hypofractionated manner has become an equivalent therapy to CRT in terms of local recurrence, survival, and toxicity. They are currently considered interchangeable, with a preference for CRT in cases where substantial downstaging is needed to achieve clear margins or to allow sphincter-sparing surgery.
Methods
Retrospective study was conducted at the University Hospital of Fuenlabrada, Madrid, analyzing real-life data on the treatment of locally advanced RC between 2011 and 2023 with RT in our center. A total of 187 patients receiving CRT and 43 receiving SCRT between 2018 and 2023. Degree of tumor regression (DTR) was evaluated with Ryan classification system.
Results
In the table, a comparison between CRT and SCRT is performed based on sex, tumor staging and use of complementary chemotherapy. Regarding DTR, complete pathological response (CPR) has been analyzed in both groups (CRT: 27% and SCRT: 23%), as well as major pathological response (Ryan classification with a score of 0 or 1) (CRT: 54% and SCRT: 39%). Chi2 test has been applied to both comparisons with no statistically significant difference between two groups (p=0.05). Table: 264P
Demographic characteristics
| SCRT | CRT | |
| Male | 65% (28) | 66% (123) |
| Female | 35% (15) | 34% (64) |
| Stage IIA | 9% (4) | 8% (14) |
| Stage IIIA | 2% (1) | 6% (11) |
| Stage IIIB | 60% (26) | 75% (141) |
| Stage IIIC | 9% (4) | 10% (18) |
| Stage IV | 19% (8) | 2% (3) |
| Chemotherapy with RT | 70% | 84% |
| N (Total) | 43 | 187 |
Conclusions
Unlike data from previous randomized clinical trials, our real-life data results, with the limitations it may have, does not show significant differences in the DTR between CRT and SCRT. This discrepancy could be attributed to several reasons (variability in patient selection, differences in the chemoradiotherapy regimens and characteristics of the study population).
Legal entity responsible for the study
The authors.
Funding
Has not received any funding.
Disclosure
All authors have declared no conflicts of interest.