Chemotherapy after surgery for stage II colon cancer makes small but real difference

Most patients who are treated for stage II colon or rectal cancer will do well, surviving for at least five years.  However, about 20 percent will not.  It hasn’t been clear whether or not chemotherapy makes a difference in survival, but a recently analyzed large study finds that it does, although the benefit is small.

The QUASAR (Quick and Simple and Reliable) clinical trial randomized more than 3,200 patients with colon or rectal cancer to receive chemotherapy or simply be observed.  Most of the patients — 91 percent — had stage II cancer where cancer cells had not yet spread to nearby lymph nodes.  Seven in ten had colon rather than rectal cancer.

Patients were treated from 1994 through 2003 in 150 centers in 19 countries.

Trial chemotherapy was 5FU (fluorouracil) modified by leucovorin (folinic acid).  Chemo was given either every week for thirty weeks or for five days in a row every four weeks for six treatments.  Since the trial began, more effective treatments using oxaliplatin, continuous infusion 5FU, or Xeloda have been found and are now in use.

After a median follow-up of 5.5 years, there were 311 deaths from any cause in the chemotherapy group and 370 in the observation-only group (relative risk 0.82) and 293 recurrences in the chemo group compared to 359 in the observation group (relative risk 0.78).  That translates to about a 3.6 percent absolute reduction in the risk of dying when chemotherapy is used — or about 4 more people in every 100 treated alive after 5 years.

Treatment effectiveness did not differ significantly by where the tumor was located, the age or sex of the patients, or which chemo regimen was used.

Interpreting the study, the QUASAR Collaborative Group headed by Dr. Robert Gray wrote,

Chemotherapy with fluorouracil and folinic acid could improve survival of patients with stage II colorectal cancer, although the absolute improvements are small: assuming 5-year mortality without chemotherapy is 20%, the relative risk of death seen here translates into an absolute improvement in survival of 3·6%.

The Group was also encouraged that,

Chemotherapy seems to prevent a proportion of recurrences and deaths, rather than just delaying them, which makes the life-years gained more substantial, especially for younger patients.

SOURCE: Gray et al, The Lancet, Number 370, Issue 9604, December 15, 2007.

More information on the study from Reuters Health , Medical News Today, and Medscape.

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