Is extramural venous invasion (EMVI) alone an indication to treat rectal cancer patients with total neoadjuvant therapy as opposed to neoadjuvant chemoradiation therapy or short course radiation therapy alone?

EMVI detected on a staging pelvic MRI for rectal cancer has been shown to be a poor prognostic factor with an increased risk for distant metastases (Siddiqui et al., PMID 28449006). EMVI was also independently associated with a positive circumferential resection margin in low rectal tumors based on data from the MERCURY II study (Battersby et al., PMID 25822672). TNT allows for earlier introduction of systemic therapy in the treatment course as well as a better chance of finishing all planned systemic therapy (Cercek et al., PMID 29566109). In addition, delivering all therapy upfront prior to surgery may help maximize the chances of a margin-negative resection. I don’t think we have strong data to support the presence of EMVI alone as a jus...