Researchers are looking for ways to accurately predict which cancer patients might avoid chemotherapy to reduce harmful side effects and unnecessary costs.. One new study used a blood test to determine which colon cancer patients might skip chemotherapy after surgery.. Another suggests that some patients at low risk of breast cancer may opt out of radiation after a lumpectomy, reports AP NEWS..

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The research was discussed at the annual meeting of the American Society of Clinical Oncology, which concluded on Tuesday in Chicago.. A colon cancer study funded by the Australian and US governments and non-profit groups has been published in the New England Journal of Medicine.

The results could allow doctors to "

But determining which patients may not need further treatment has proven difficult.. Scientists study whether a blood test can help doctors make a decision.

The study involved 455 patients with colon cancer. After surgery, one group of patients underwent a blood test, taking into account the genetic profile of the tumor, in order to detect the remaining particles of cancerous DNA..

If the analysis showed no signs of cancer, patients did not receive chemotherapy. For the rest of the patients, doctors made decisions about chemotherapy in the usual way, guided by an analysis of the tumor and nearby tissues.. About 93% of patients from both groups were free of cancer after two years..

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Avoiding chemotherapy "

In another study, 500 older women with advanced early-stage breast cancer and low levels of the Ki67 protein, a marker of fast-growing cancer, took part..

After the operation, the women took hormone-blocking pills, the standard treatment for this type of cancer, but did not receive radiation therapy.. Five years later, only 10 women had cancer back and one woman died.. There was no comparison group, but the investigators stated that the results were comparable to those of similar patients who underwent radiation..

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