Colorectal Cancer is the third-most common cancer and second most common cause of cancer-related death worldwide, and rectal cancer specifically accounted for 30 % to 40 % of all new colorectal cancer diagnoses from 2015–2019.1 Improvements in screening, systemic therapies, radiation technology, and surgical techniques have all contributed to increases in overall and disease free survival for colon and rectal cancer patients.2

Over the last 40 years, management of locally advanced (Stage II & III) rectal cancer has shifted away from a surgery-first paradigm to increasing amounts of neoadjuvant treatment with resultant improvements in local recurrence rates, disease-free and overall survival, and increased rates of sphincter-preservation.3, 4, 5 The current American College of Colon and Rectal Surgeons clinical practice guidelines recommend total neoadjuvant therapy (TNT), comprised of both chemoradiation and chemotherapy, for patients diagnosed with stage II or stage III, also known as locally advanced rectal cancer.6 Compared to patients who receive neoadjuvant chemoradiation therapy (nCRT) and adjuvant chemotherapy, patients who undergo TNT have higher rates of therapy completion, decreased disease-related treatment failure, and increased rates of both pathologic and clinical complete response (pCR and cCR, respectively).7, 8, 9

Improvement in rectal cancer cCR rates, defined as the absence of clinical, endoscopic, or radiologic evidence of residual cancer after any neoadjuvant therapy, has been reported as high as 51–74 % after TNT and has prompted further research into organ preservation for rectal cancer patients.10, 11, 12 A non-operative surveillance strategy, also known as Watch and Wait (WW), was first proposed by Dr. Habr-Gama and her group in 2004 to avoid an operation with high morbidity and long-term consequences.13, 14, 15, 16 Although exact surveillance protocols vary by institution and physician, monitoring consists of frequent clinical and endoscopic exams, labs, and CT and MRI imaging. The risk of local regrowth after achieving cCR ranges from 15 % to 36 %, with a significant decrease in local regrowth after three years.12,17,18 When this does occur, salvage surgery may be offered with good outcomes, with R0 resection achievable in over 95 % of patients. Oncologic outcomes such as disease-free survival after salvage surgery were not significantly different compared to standard surgical resection.18

Although WW does spare the morbidity and mortality of surgery, LARC patients still undergo systemic chemotherapy and chemoradiation treatments, which also come with adverse effects that can limit quality of life. In a prospective study by Custers et al., functional and quality of life outcomes for patients with rectal cancer in WW were measured along their surveillance course.19 A quarter of patients experienced bowel dysfunction at 3 months that can persist for as long as 24 months. Sexual dysfunction was also reported by 32 % of males at 24 months and women reported decreased sexual satisfaction after treatment as well. Despite good oncologic outcomes, patients who had to undergo salvage resection for local regrowth reported significantly worse functional outcomes after surgery compared to those who remained in WW.

Despite an overall decrease in incidence of both colon and rectal cancers since 1990, the incidence of rectal cancer in individuals younger than 50 years has increased by about 2 % per year in the last decade.2 It is even estimated that by 2030, 25 % of rectal cancers will be diagnosed in individuals younger than 50 years.20 Early-Onset Rectal Cancer (EORC) presents several challenges, as patients often present with more advanced disease compared to patients diagnosed after age 50, and EORC patients have higher rates of worrisome tumor features such as presence of signet ring cells and mucinous histology.21 Despite these worrisome features, several studies have found similar or better rates of stage-for-stage disease free survival and overall survival for EORC patients compared to patients diagnosed after age 50.20, 21, 22, 23 Historical data suggests that EORC patients were likely to undergo more aggressive treatment compared to older patients, perhaps due to their more advanced stage at presentation.24

Given the rising incidence of early-onset rectal cancer, considerations must be made for how to best approach management of these patients. Organ-preservation treatment with watch-and-wait strategies offer an appealing alternative to major surgery for EORC patients who achieve complete clinical responses after neoadjuvant therapy, however, there may be hesitancy in watch-and-wait enrollment for young patients given their longer life expectancy. The aim of this review is to discuss the role of the watch-and-wait strategy in early onset rectal cancer.