Second St. Gallen European Organisation for Research and Treatment of Cancer Gastrointestinal Cancer Conference: consensus recommendations on controversial issues in the primary treatment of rectal cancer

Abstract

Primary treatment of rectal cancer was the focus of the second St. Gallen European Organisation for Research and Treatment of Cancer (EORTC) Gastrointestinal Cancer Conference. In the context of the conference, a multidisciplinary international expert panel discussed and voted on controversial issues which could not be easily answered using published evidence. Main topics included optimal pretherapeutic imaging, indication and type of neoadjuvant treatment, and the treatment strategies in advanced tumours. Here we report the key recommendations and summarise the related evidence. The treatment strategy for localised rectal cancer varies from local excision in early tumours to neoadjuvant radiochemotherapy (RCT) in combination with extended surgery in locally advanced disease. Optimal pretherapeutic staging is a key to any treatment decision. The panel recommended magnetic resonance imaging (MRI) or MRI + endoscopic ultrasonography (EUS) as mandatory staging modalities, except for early T1 cancers with an option for local excision, where EUS in addition to MRI was considered to be most important because of its superior near-field resolution. Primary surgery with total mesorectal excision was recommended by most panellists for some early tumours with limited risk of recurrence (i.e. cT1-2 or cT3a N0 with clear mesorectal fascia on MRI and clearly above the levator muscles), whereas all other stages were considered for multimodal treatment. The consensus panel recommended long-course RCT over short-course radiotherapy for most clinical situations where neoadjuvant treatment is indicated, with the exception of T3a/b N0 tumours where short-course radiotherapy or even no neoadjuvant therapy were regarded to be an option. In patients with potentially resectable tumours and synchronous liver metastases, most panel members did not see an indication to start with classical fluoropyrimidine-based RCT but rather favoured preoperative short-course radiotherapy with systemic combination chemotherapy or alternatively a liver-first resection approach in resectable metastases, which both allow optimal systemic therapy for the metastatic disease. In general, proper patient selection and discussion in an experienced multidisciplinary team was considered as crucial component of care.

Short course radiation as a component of definitive multidisciplinary treatment for select patients with metastatic rectal adenocarcinoma

“…Our results suggest that outcomes are encouraging for select patients with metastatic rectal cancer treated with a definitive multidisciplinary approach that included chemotherapy followed by SCRT followed by pelvic surgery a median IQR of 6 [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22] days later. Given the observed benefit of "short course, long interval" treatment outlined above for patients with localized rectal cancer (15)(16)(17), there is likewise interest in incorporating a planned break between SCRT and pelvic surgery for patients with metastatic disease during which additional chemotherapy can be administered.…”

“…However, 5 to 6 weeks of long-course CRT followed by a 6-8 weeks interval between completion of radiation and surgery may allow for disease progression due to lack of exposure to combination systemic therapy during this period. Thus, the American College of Radiology appropriateness guidelines state that preoperative SCRT can be considered for patients with metastatic disease for whom definitive management of the primary is desired (13), and a recent EORTC consensus statement on M1 rectal cancer actually recommends preoperative SCRT in this setting (14).…”

Role of ultrasound in colorectal diseases

“…In case of early rectal tumors, the high resolution of RUS makes it even superior in distinguishing T1 and T2 tumors with a specificity of 86% (95%CI: 80%-90%) compared to 69% (95%CI: 52%-82%) for MRI[70]. According to the consensus recommendation of the European Organisation for Research and Treatment of Cancer in 2014, RUS is the preferable modality of staging in T1 tumors, whereas otherwise the combination of MRI and RUS is beneficial in advanced stages, regarding the fact that MRI provides better assessment of the mesorectal fascia[68,71]. …”

“…According to a meta-analysis covering 33 studies, it has a moderate diagnostic value in preoperative nodal staging with a pooled sensitivity and specificity of 69% (95%CI: 0.63-0.75) and 77% (95%CI: 0.73-0.82), respectively[72]. Only perirectal lymph nodes can be assessed with RUS, the evaluation of the entire mesorectal area requires high-resolution MRI with appropriate “rectal cancer protocol”[71,73]. Nodal staging is basically based on morphological characteristics (size greater than 5 mm, mixed signal intensity, irregular borders, and spherical rather than ovoid or flat shape)[74].…”

What is most relevant in preoperative rectal cancer chemoradiotherapy – the chemotherapy, the radiation dose or the timing to surgery?

“…Thus, scRT is sufficient, although it could be discussed whether surgery alone would be enough for some of them to obtain excellent locoregional control. It should be said that these guidelines are far from generally accepted, and CRT rather than surgery alone or preceded by scRT is recommended by many in spite of no need to downstage/size the tumor, as, for example reflected in a document after a recent EORTC consensus meeting [10].…”