Colorectal cancer affects the large intestine and the rectum, and it is one
of the most common cancers in the United States, with over 200,000 cases being reported. The majority of these cases are people who are 45 or older, thus they need frequent screenings to ensure that they are healthy. Sadly, a lot of these cases get to the late stages of cancer, meaning they already spread to other organs because a majority of the population goes against the advice of physicians. When the cancer gets to stages III or IV, the chances of having a 5-year relative survival rate is approximately 13%, however in stages I or II, the chances increase up to 90%. Some ways people get tested for colorectal cancer are colonoscopy, biopsy, immunohistochemistry, and digital rectal exam (DRE) just to name a few. Colonoscopies are done by gastroenterologists, who are doctors that treat diseases of the digestive system, and they insert a flexible tube that has a camera at the end of it to check for abnormalities. Biopsies usually accompany colonoscopies, in which when the doctor sees an abnormality, they use forceps to take a piece of the abnormal tissue and send it to the laboratory to be analyzed. Immunohistochemistry is a type of blood test, in which it analyzes the specific antigens, which are proteins found on the surfaces of cells, in the blood to see whether or not they match those found on certain tumors. DREs are actually the oldest test out of the few that have been mentioned, which involved the doctor feeling for tumors in the rectum using a lubricated glove.
Now that we understand what colorectal is and how it is tested, we can talk about the
major breakthrough that Memorial Sloan Kettering (MSK) Cancer Hospital had not that long
ago. They were experimenting with a new drug that falls into the category of immunotherapy, which is when they make the immune system know what cells to attack and how to attack them. Their category of colorectal cancer patients fell into those who have mismatch repair-deficient (MMRd) or microsatellite instability (MSI). MMRd is a specific genetic makeup which is where the genes of the cancer cell are prone to make even more abnormalities and defects, but only 5-10% of cancer patients have this kind of tumor. If this cancer has so many defects, why can’t the immune system attack it? Here’s the thing, our immune system has a certain safety mechanism called a checkpoint, which prevents it from attacking normal functioning human cells. These cancer cells can trick this mechanism and make the immune system think that they are normal, functioning cancer cells, which lets the tumor grow without any disturbance. However, there are drugs known as checkpoint inhibitors which, as the name suggests, inhibit the checkpoint mechanism. Now the immune system finally recognizes these cells and notices that they are extremely abnormal, thus attacking them. There were a lot of risks in taking this drug, known as dostarlimab, but the doctors monitored the patients in the trial and assessed the risks beforehand. They made sure the tumor shrunk enough using chemotherapy and radiation so they could carry out the administering of the drug. With all this information in mind, they came up with really surprising results. 100% OF THE PATIENTS NO LONGER HAD THE CANCER. They administered the drug through the vein every three weeks for 6 months and 0 of the patients had cancer. This is an amazing breakthrough in oncology, and of course, there is more research to come with this so we can attempt to treat other kinds of cancer. But, as Neil Armstrong said, “One small step for man, one giant leap for mankind.”
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