What are the effects of preoperative radiotherapy on rectal adenocarcinoma (rectal cancer)?

From the Guidelines

The correct answer regarding preoperative radiotherapy for rectal adenocarcinoma is D, as it reduces the risk of local recurrence and improves outcomes in rectal cancer. This neoadjuvant approach has become standard practice for locally advanced rectal cancers (typically T3-T4 or node-positive disease) [ 1 ]. Preoperative radiotherapy works by shrinking tumors before surgery, which can down-stage the tumor. While preoperative radiotherapy does increase some postoperative morbidity, this is considered acceptable given the benefits in local control [ 1 ]. Importantly, preoperative radiotherapy has not consistently demonstrated an overall survival benefit when used alone, though it significantly reduces local recurrence rates.

Key Points

• Preoperative radiotherapy reduces local recurrence rates in rectal cancer [ 1 ]
• The treatment is typically delivered as either short-course radiotherapy or long-course chemoradiotherapy [ 1 ]
• Preoperative radiotherapy has not consistently demonstrated an overall survival benefit when used alone [ 1 ]
• The approach is considered acceptable given the benefits in local control, despite increasing some postoperative morbidity [ 1 ]

Treatment Options

• Short-course radiotherapy (25 Gy in 5 fractions) followed by immediate surgery
• Long-course chemoradiotherapy (45-50 Gy over 5-6 weeks with concurrent chemotherapy) followed by surgery after 6-10 weeks [ 1 ]

From the Research

Preoperative Radiotherapy for Rectal Adenocarcinoma

• The use of preoperative radiotherapy in the treatment of rectal adenocarcinoma has been studied extensively, with various regimens and outcomes reported 2, 3, 4, 5, 6.
• Preoperative radiotherapy can down-stage tumors, with one study reporting a complete clinical response in 9 out of 19 patients who underwent post-treatment endoscopic evaluation 2.
• The addition of consolidation neoadjuvant chemotherapy after short-course preoperative radiotherapy has been shown to achieve oncologic outcomes comparable to those of short-course radiation therapy alone or long-course chemoradiotherapy 2.
• Preoperative radiotherapy has been associated with a reduced risk of local recurrence, with one study reporting an overall local recurrence rate of 9.8% 4.
• The optimal fractionation and timing of surgery in relation to radiotherapy remains controversial, with randomized trials showing that delaying surgery after short-course radiotherapy and adding consolidation chemotherapy may result in better short-term overall survival and lower acute toxicity 6.

Outcomes and Morbidity

• Preoperative radiotherapy has been associated with significant morbidity and mortality, including intraoperative bleeding, perineal wound infection, and abdominal wound infection 4.
• The use of preoperative radiotherapy has also been associated with an increased risk of postoperative complications, including Clavien-Dindo Grade 3 complications 2.
• However, the addition of consolidation neoadjuvant chemotherapy after short-course preoperative radiotherapy has been shown to be well-tolerated, with a low rate of grade 3 or higher adverse events 2.

Comparison of Regimens

• The comparison of short-course and long-course radiotherapy regimens has shown that both can be effective in reducing the risk of local recurrence, but the optimal regimen remains unclear 3, 5, 6.
• One study reported that preoperative radiotherapy, either short-course or long-course, was associated with better local control and overall freedom from disease compared to postoperative radiotherapy 5.
• The use of concurrent chemotherapy with preoperative radiotherapy has also been studied, with some trials showing improved outcomes, but the optimal regimen remains unclear 5, 6.