Chemotherapy is great for annihilating cancer cells, but it can result in life-changing side effects if regular cells end up in the crossfire.
Chemotherapy can be both an art and a science if you know how to tell if someone needs it. A new study shows that a technique that helped some stage II colon cancer patients avoid Chemo has no effect on their clinical outcomes.
The technique used in this study is called circulating tumorDNA. Small sections of fragmented DNA from tumors that are circulating in the blood stream is what this is. They are not part of a tumor cell at all.
Circulating tumor DNA (ctDNA) and how it's found in blood. (Racheljunewong/Wikimedia).
Researchers know that the presence of ctDNA in the bloodstream after surgery is related to the risk of cancer regrowth.
This knowledge has been further advanced by the new study. The first clinical study to show that a ctDNA guided approach can benefit the patients is looking at stage II colon cancer.
Anne Marie Lennon says that stage II colon cancer is a unique challenge.
Patients in stage I colon cancer don't receive treatment because of their high survival rate. The benefits of the therapy are not worth the risks. Every stage III colon cancer patient is currently receiving chemotherapy because of the high risk of relapsed.
Stage II colon cancer has spread through the muscle layers of the colon wall but hasn't spread to other organs. In this case, the patient will have to have surgery to remove the tumor, but the clinician will have to make a decision on whether or not the patient also undergoes Chemo after that.
Approximately 75 percent of people with stage II colon cancer don't need to use drugs after their surgery. Getting it wrong can be fatal if you don't work out which patients will benefit the most from the treatment.
If the cancer has broken all the way through into other tissue, for example, or if the tumor looks abnormal under the microscope, it could prompt the doctor to book a course of treatment.
A new study shows that this method isn't perfect, and that many cancer patients might be getting Chemo when they don't need it.
A total of 455 patients with colon cancer were recruited to the study. The ctDNA guided approach was assigned to 302 of the others. The study had data on the patients for 3 years after 37 months.
Both the standard management and the guided treatment had the same rates of survival. The amount of treatment that was given was different. In the standard treatment group, more than two thirds of patients underwent chemo, while in the ctDNA guided treatment group only 15% had to.
For no increase in survival or decrease in tumor recurrence, that's almost double the number of patients who were treated with Chemo.
The researchers wrote that a ctDNA-guided approach to stage II colon cancer reduced the use of drugs.
There is a survival benefit from the low recurrence rate in ctDNA-positive patients.
The researchers hope ctDNA could be a helpful indicator for how to treat other types of cancer and other stages of colon cancer, and the team is already working on early stage Pancreatic and stage III colon cancer to see if ctDNA can help there as well.
Joshua Cohen is a researcher from the University School of Medicine.
A stage II colon cancer patient who is negative for ctDNA has a lower chance of cancer coming back than the average stage I colon cancer patient.
The research will be published in the New England Journal of Medicine.
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