Researchers have developed a dynamic clinical calculator that estimates conditional recurrence-free survival (RFS) after total neoadjuvant therapy (TNT) for rectal cancer. 

The calculator could help guide decisions about whether to proceed with surgery or undergo watch-and-wait observation, according to researchers. They described the calculator in JAMA Network Open.

The researchers noted that the likelihood of RFS for a patient undergoing watch-and-wait management can change over time, and current models only provide a static prediction after resection of the primary tumor.

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Therefore, the researchers attempted to develop a calculator that could show RFS dynamically at different time points. The team incorporated conditional modeling into a previously validated clinical calculator to allow the probability of RFS to be updated based on whether surgery or observation was chosen. 

The researchers then tested the calculator in 302 patients with stage II-III rectal cancer diagnosed from 2009 to 2015. In this cohort, 68% of patients underwent surgery within 3 months of TNT completion, 18% were initially managed with watch-and-wait but underwent surgery more than 3 months after TNT completion, and 14% of patients remained in watch-and-wait management throughout follow-up. 

Among the patients who initially selected watch-and-wait, the switch to surgery tended to occur within the first year. RFS was not significantly different whether surgery was performed at 3.0 to 5.9 months, 6.0 to 11.9 months, or 12 months or more from TNT. The RFS rates were 73%, 71%, and 70%, respectively. 

“This finding indicates that oncologic outcome was not compromised by the delay,” the researchers wrote.

They noted that the RFS curves for patients in watch-and-wait at 12 months were similar to those for patients who had undergone surgery and had a pathologic complete response. 

The researchers also noted that the model performance improved over time, with the concordance index increasing from 0.62 at 3 months after TNT to 0.66 at 12 months. 

“The risk calculator provided conditional survival estimates at any time during surveillance and could help physicians counsel patients with rectal cancer about the consequences of alternative treatment pathways and thereby support informed decisions that incorporate patients’ preferences,” the researchers concluded.

Disclosures: Some study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of disclosures.


Weiser MR, Chou JF, Kim JK, et al. A dynamic clinical calculator for estimating conditional recurrence-free survival after total neoadjuvant therapy for rectal cancer and either surgery or watch-and-wait management. JAMA Netw Open. Published online September 29, 2022. doi:10.1001/jamanetworkopen.2022.33859