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PROSPECT: What the Colorectal Cancer Trial Found
PROSPECT tested giving chemotherapy alone before rectal cancer surgery, with radiation kept in reserve. Five-year results were no worse, and most people avoided pelvic radiation entirely.
Original commentary from the Cancer Explained editorial team.
Please note: this page is educational only — it is not medical advice, and it does not speculate about anyone’s health beyond reliable public reporting. For questions about your own health, talk with your healthcare team.
A trial about taking something away
Most cancer trials add a drug. PROSPECT asked whether a treatment already in routine use could be removed for some people without costing them anything.
The treatment in question is pelvic radiation before rectal surgery. It works. It also carries long-term effects on the bowel, the bladder, sexual function and fertility, and those effects last for the rest of a person's life.
Who was eligible
1,194 adults were randomly assigned, and 1,128 started treatment. All had rectal cancer staged as T2 with positive nodes, T3 with negative nodes, or T3 with positive nodes. All were candidates for surgery that would preserve the anal sphincter.
585 people started FOLFOX chemotherapy alone before surgery. 543 started standard chemoradiotherapy.
The FOLFOX group did not simply go without radiation. It was held in reserve. Anyone whose tumor shrank by less than 20%, or who had to stop FOLFOX because of side effects, went on to have chemoradiotherapy after all.
Five years on, the two paths matched
At a median follow-up of 58 months, the hazard ratio for the cancer returning or death was 0.92, with a 90.2% confidence interval of 0.74 to 1.14 (P=0.005 for non-inferiority). The upper end stayed below the line set in advance, so FOLFOX was declared no worse.
Five-year disease-free survival was 80.8% with FOLFOX (95% CI 77.9 to 83.7) and 78.6% with chemoradiotherapy (95% CI 75.4 to 81.8).
Overall survival was similar too (hazard ratio 1.04; 95% CI 0.74 to 1.44), as was the cancer returning in the pelvis (hazard ratio 1.18; 95% CI 0.44 to 3.16).
The one in ten who still needed radiation
In the FOLFOX group, 53 people (9.1%) had chemoradiotherapy before surgery anyway, and 8 more (1.4%) had it afterwards.
That is the honest shape of the finding. This is selective omission, not abolition. About one person in ten still ends up having radiation, and nobody knows in advance who that will be.
What this trial cannot tell you
- It covers a specific, lower-risk group. It says nothing about T4 tumors, bulky nodal disease, or a tumor threatening the surgical margin.
- Nobody was blinded. Patients, surgeons and radiologists all knew which path a person was on.
- Local recurrence was rare in both groups, so the confidence interval around that comparison runs from 0.44 to 3.16. A real difference in either direction cannot be ruled out.
- FOLFOX has its own burden, including nerve damage from oxaliplatin. Avoiding radiation is not the same as avoiding harm.
Questions about treatment before rectal surgery
- What is my clinical T and N stage, and does it match the group in this trial?
- Am I a candidate for sphincter-sparing surgery?
- If my tumor does not shrink enough on chemotherapy, what happens then?
- Which long-term effects of pelvic radiation matter most in my situation?
Sources
This article was written from the sources below, which were checked on the source-check date shown above.
How this article was prepared
Prepared by Cancer Explained's AI-assisted editorial system and checked against the sources listed below. This article has not been reviewed by a healthcare professional unless a named reviewer is specifically shown.
Cancer Explained is published by the National Cancer Information Foundation as a nonprofit-oriented public-interest education project. It is not a diagnostic service, does not recommend treatments, and is not for emergencies.
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Prevention, possible warning signs, screening, and diagnosis
This story relates to Colorectal cancer. The information below is general: it does not reveal anything else about a public person’s health, and not every point applies to every cancer. Personal advice depends on age, symptoms, family history, exposures, and medical history.
Prevention and risk reduction
Not every cancer can be prevented. Avoiding tobacco, protecting skin from ultraviolet radiation, limiting alcohol, staying active, and receiving recommended HPV or hepatitis B vaccination can lower the risk of certain cancers. A risk factor is not a prediction or a cause in one individual.
Symptoms and possible early signs
Possible signs vary and are often caused by conditions other than cancer. Changes worth discussing include a new lump, unexplained bleeding or weight loss, a persistent cough, lasting bowel or bladder changes, a changing skin spot, or symptoms that persist or worsen. Some early cancers cause no symptoms.
Screening and early detection
Screening looks for certain cancers before symptoms begin. Recommended tests exist only for some cancers and depend on age and risk. Screening can have benefits and harms; it is not the same as evaluating a new symptom, and there is no single routine scan or blood test that reliably screens for every cancer.
How cancer is diagnosed
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