Colon cancer's location may determine patient survival
Staff Writer |
Where in the colon a cancer develops could affect a patient's chances for survival, a new report finds.
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At issue are so-called left-sided and right-sided colon cancers, one oncologist who reviewed the findings explained.
"Left-sided cancers are located closer to the anus and located in the rectum, sigmoid colon and descending colon," said David Bernstein, chief of hepatology at Northwell Health in Manhasset, N.Y.
"These cancers usually present with bleeding or partial obstruction [and] because of this presentation, patients tend to seek medical care earlier."
On the other hand, "right-sided lesions - located in the first part of the colon, near the junction with the small intestine - do not typically present with obstruction but tend to present with anemia and are more likely to be associated with metastatic disease, especially to the liver," Bernstein said.
Because they are often detected later in their progression, these right-sided colon tumors, "have a worse prognosis than left-sided colon cancers," he said.
That's what the new study found, as well. A team led by Dr. Fausto Petrelli, of the ASST Bergamo Ovest, in Treviglio, Italy, reviewed data from 66 studies. The studies involved a total of more than 1.4 million patients followed for a median of more than five years.
The result: colon cancer patients with left-sided tumors were nearly 20 percent less likely to die than those whose tumors occurred on the right side.
And there seemed to be more at play than simply later detection, the Italian team noted. The difference in survival between left- and right-sided colon cancer held even after the researchers factored out cancer stage at diagnosis, the study authors said.
Petrelli's group pointed to prior research that has shown that right and left colon cancers are genetically distinct, as well.
Based on the new findings, the study authors believe that "primary tumor locations should be carefully considered when deciding treatment intensity." ■