PH-0105 Prediction of clinical complete response in rectal cancer using clinical and radiomics features

751 Background: The Lyon R96-02 randomized trial has demonstrated in T2-3 rectal cancer that external beam radiotherapy (EBRT) with Contact X Ray brachytherapy (CXB) boost was increasing clinical complete response, sphincter preservation and in early cases organ preservation. We report French experience in 3 radiotherapy departments using CXB boost with chemoradiotherapy (CRT) in early T2T3N0. Methods: Selection based on digital rectal examination, colonoscopy, MRI (and/or Endorectal-ultrasound). Inclusion : adenocarcinoma (distal, middle rectum), T2 T3a-b, tumor diameter ≤ 4cm, N0, M0. Treatment : CXB (80-110 Gy/3-4 fr) followed by CRT (CAP 50). Tumor response assess on week 14 : DRE, rigid rectoscopy and MRI. Clinical complete response (cCR) defined as no visible tumor, supple rectal wall and TRG 1-2 on MRI. In case of cCR a close surveillance or local excision was proposed. Results: Between 2002 -2016, 84 patients treated. Median age: 75 years, Male: 59, Female: 25. Operable patients: 69 (83%). T2 : 52, T3 : 32 (Lyon Villeurbanne : 16, Macon : 11, Nice : 57). Median follow-up time : 53 months. cCR was achieved in 94% of cases. Local excision performed in 17 patients (ypT0 : 16). At 4 years, the cancer specific survival was 82% [CI:96-70] and the local relapse rate 12% [CI: 2-22]. No isolated perirectal lymph node relapse observed. After 4 years, 3 more local relapses observed (4, 6, 7 years). Main late toxicity ( > 6 months after treatment) was rectal bleeding (radiation telangiectasia) which required plasma argon coagulation in 5 patients. No TME surgery was performed and organ preservation was achieved in all cases. Bowel function was good in 85% of patients (LARS score < 20). Conclusions: When combining CXB with CRT, rectal cancer T2T3a-b N0 ≤4cm achieve a high rate of cCR (≥85%) with organ preservation, good bowel function, low rate of local relapse ( < 15%) and low toxicity. As rectal adenocarcinoma is radioresistant, the treatment must use a CXB boost. Like anal squamous cell cancer, planned organ preservation can be proposed to operable patients. The ongoing European OPERA trial aims at bringing evidence to this option.

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Organ preservation in rectal cancer patients treated with total neoadjuvant therapy.

Journal of Clinical Oncology ◽

10.1200/jco.2019.37.4_suppl.692 ◽

2019 ◽

Vol 37 (4_suppl) ◽

pp. 692-692

Author(s):

Rosa Maria Jimenez-Rodriguez ◽

Felipe Fernando Quezada-Diaz ◽

Irbaz Hameed ◽

Sujata Patil ◽

Jesse Joshua Smith ◽

...

Keyword(s):

Rectal Cancer ◽

Neoadjuvant Therapy ◽

Cancer Patients ◽

Rectal Adenocarcinoma ◽

Case Series ◽

Complete Response ◽

Stage Ii ◽

Clinical Complete Response ◽

Mri Staging ◽

Total Neoadjuvant Therapy

692 Background: Retrospective case series suggest that watch-and-wait (WW) is a safe alternative to total mesorectal excision (TME) in selected patients with a clinical complete response (cCR) after chemoradiotherapy (CRT). Because treatment strategies vary widely and total numbers of patients treated at different institutions have not been reported, the proportion of rectal cancer patients who can potentially benefit from WW is not known. Here, we report the results of a treatment strategy incorporating WW in a cohort of rectal cancer patients treated with total neoadjuvant therapy (TNT). Methods: Consecutive patients with stage II/III (MRI staging) rectal adenocarcinoma treated with TNT from 2012 to 2017 by a single surgeon were included. TNT consisted of mFOLFOX6 (8 cycles) or CapeOX (5 cycles) either before or after CRT (5600 cGy in 28 fractions with sensitizing fluorouracil or capecitabine). Tumor response was assessed with a digital rectal exam, endoscopy, and MRI according to predefined criteria. Patients with a cCR were offered WW, and patients with residual tumor were offered TME. WW and TME patients were compared based on intention to treat, using the chi-square or rank sum test. Relapse-free survival (RFS) was evaluated by Kaplan-Meier analysis. Results: A total of 109 patients were identified. One patient died during CRT. Of the 108 patients, 64 (59%) had an incomplete clinical response; 4 of the 64 patients declined surgery or had local excision, and 60 underwent TME. The remaining 44 patients (41%) had a cCR and underwent WW. On average, patients in the WW group were older and had smaller, more distal tumors. Median radiation dose, number of chemotherapy cycles, number ofadverse events, or length of follow-up (28 months) did not differ between the TME and WW groups. Five (11%) of the 44 WW patients had local tumor regrowth, at a median of 14 (4–25) months after TNT; 2 of the 5 also had distant metastasis. Six (10%) of the 60 TME patients had a pathological complete response. RFS did not differ between the TME and WW groups (log rank P= 0.09). Conclusions: Approximately 40% of patients with stage II/III rectal cancer treated with TNT achieve a clinical complete response and can benefit from a WW approach with the aim of preserving the rectum.

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