In fact, precisely these differences, very well documented in medical records accumulated by health professionals, are what have allowed us to create a new molecular classification in colon cancer that, as pointed out by Dr. Jose Maria Vieitez, head of Digestive Tumors with the Medical Oncology Service at MD Anderson Cancer Center Madrid – Hospiten, "will be the new way to treat colon tumors in the future". This was announced by the specialist at the Congress "Perspectives in Oncology", organized by the Portuguese Society of Medical Oncology from February 16 to 17 in Oporto, a meeting of excellence in the field of oncology to which this specialist has been invited as a reference expert on the subject.
As he himself explained, this molecular classification will be possible because it has been proven that "when comparing molecular data with location data, the results suggest that subtypes 2 are located in the left colon and subtypes 1 in the right colon". Thus, it is the distinctive biological characteristics between left colon cancer and right colon cancer that will allow health professionals to treat patients with colon cancer in the future according to their molecular characterization rather than their anatomical location.
Differences between right and left colon cancer
In addition to a different prevalence (70% of the tumors originate in the left colon and 30% in the right colon), the symptoms of the patients may also vary depending on the location of the cancer. Thus, while patients with left colon cancer usually suffer from rectal bleeding or anal bleeding, and colic-type pain that warns of the presence of the disease, patients with right colon cancer do not suffer from these symptoms until the tumor is in a much more advanced stage. "The symptomatology in the right colon produces less colic pain and appears more slowly and sneaks up on us," says Dr. Vieitez, who also highlights important differences in screening.
The appearance of the pre-neoplastic lesion, i.e, of the lesion that appears in the colon a few years before the cancer develops, varies greatly depending on the location, on the left or right, of the tumor. Thus, polyps that appear in the right colon are usually flat and their detection is much more complicated than that of polyps that appear in the left colon, which have a more typical prominent appearance towards the intestinal lumen. In fact, these diagnostic difficulties cause right colon cancer to be often detected later than left colon cancer.
Some data that do not translate into higher mortality in right colon cancer, because, as Dr. Vieitez points out, "when the tumor is detected early, without having metastasized, the treatment probably has a similar impact in both locations". In addition, the doctor continues, "right colon cancer has some peculiarities that usually translate into a better prognosis when it is detected without lymph node involvement".
Despite this, this specialist emphasizes the importance of refining the prognosis not only based on the location of the tumor, but also on aspects such as the size of the tumor, the involvement or not of lymph nodes, the presence of metastasis, and certain molecular characteristics recognized as response predictors. A whole series of data that, together with the location of the tumor, in the left or right colon, allow the specialist to establish the best possible treatment for patients with colon cancer.