Risk factors for regrowth identified in patients with rectal cancer

Aggressive tumor characteristics were associated with the risk of regrowth in patients with rectal cancer in a new study presented at Digestive Disease Week (DDW) 2024 by Neal Bhutiani, MD, PhD, an advanced surgical oncology researcher at the colon and rectal at the University of Texas. MD Anderson Cancer Center.

“The option of non-surgical management after neoadjuvant treatment is very attractive to patients,” says Dr. Bhutiani. “When compared to the potential side effects of a rectal resection, many patients prefer a watch-and-wait approach. If we can better understand who is likely to experience regrowth after neoadjuvant therapy, we can be more confident when telling patients whether surveillance or resection is right for them.

“Our study reinforces that ‘watch and wait’ is a viable treatment strategy, including for patients with some of these risk factors,” he says. “We discuss the potential for non-operative management with patients from the first time they meet us throughout their treatment journey. This data can inform this discussion and help set expectations.

The study included 126 patients with rectal cancer treated with neoadjuvant radiotherapy and/or chemotherapy. All patients had a complete clinical response (cCR) or near-cCR and were therefore eligible for nonoperative management.

Key findings after a median follow-up period of 33 months include:

• The regrowth rate was consistent with previous studies.
• Regrowth usually occurred locally. Twenty-seven patients (21.4%) showed local regrowth while eight (6.3%) showed distant metastases.
• Aggressive tumor characteristics were associated with a higher risk of regrowth. Extramural vascular invasion (EMVI) and clinically positive pelvic sidewall lymph nodes were associated with a higher risk of regrowth.
• Patients with near RCC may be at higher risk of late regrowth. Overall, regrowth-free survival was similar between patients with cCR and near RCC at initial post-treatment endoscopic evaluation. However, after one year, patients with initial CRC tended to have a lower risk of regrowth.

Extramural vascular invasion and clinically positive pelvic sidewall lymph nodes are known features of aggressive tumor biology, but this is the first time they have been associated with tumor regrowth. This may be partly because these high-risk patients have not always been included in studies evaluating nonsurgical management of rectal cancer, according to Dr. Bhutiani.

The fact that most regrowth occurred locally suggests that some residual tumor cells are undetectable by current methods, says Dr. Bhutiani, despite the strict criteria for CRC: patients undergo a digital rectal exam, endoscopic evaluation and high-quality magnetic resonance imaging.

“We do the best we can with the tools we have,” he says. “But our tools are not perfect. Even with all of our new multimodal treatments, tumor biology ultimately determines outcome.

Dr. Bhutiani and colleagues are currently looking for additional risk factors for tumor regrowth to see if patient genetics and the tumor's immunological profile can predict the likelihood of regrowth.

Ultimately, they hope an objective calculator or risk score can be used to stratify patients and determine who is appropriate for surveillance and who requires surgery.

This Press release was published by the DDW 2024 on May 20, 2024.

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