Colorectal cancer is the third most common cancer diagnosed in the United States, with a 5 year surviving rate of less than 10 % for patients with metastatic disease.
Unfortunately colorectal cancers (CRC) develop insidiously and may therefore go undetected for long periods. Cecal and right sided colon cancers call clinical attention by appearance of fatigue and weakness due to iron deficiency anemia. Left-sided colorectal adenocarcinomas may produce occult bleeding or cramping in the left lower quadrant.
Studies of colorectal carcinogenesis have shown molecular heterogeneticity and different mutations in the tumoral cells. The epidermal growth factor receptor (EGFR) – signaling pathway is generally up-regulated in the colorectal cancer. Two of the many signaling molecules of the EGFR are RAS (a G protein) and the protein kinase RAF. More than half of human colorectal cancers carry either one of these mutations making these types of cancers very refractory to targeted therapies.
In a new study a group of researchers found that high doses of vitamin C (equivalent to the levels found in 300 oranges) impaired the growth of KRAS mutant and BRAF mutant colorectal tumors in mice.
What is well known until now about vitamin C is the fact that it is an antioxidant and that is why prevents or delays some types of cell damage. Based on recent data the group discovered that the opposite was true when we talk about high doses of Vitamin C.
In an oxygen-rich environment (such as arterial blood), a portion of vitamin C (ascorbic acid) is oxidized and is transformed in a compound called dehydroascorbic acid (DHA).
A membrane protein, glucose transporter GLUT1, allows this new compound to enter the cell, but this activity is not afforded for ascorbic acid. Once inside the cell, the natural antioxidant inside the cancer cell try to convert DHA into ascorbic acid. In this continuous process all the antioxidants are depleted and the cancer cell dies from oxidative stress. Another fact is that, KRAS and BRAF mutant cells produce more reactive oxygen species (ROS) than normal cells, that’s why they need more antioxidants in order to survive.
Vitamin C, this natural and inexpensive molecule, can be used as the definitive solution or as adjuvant therapy in treating malignancies.
Further studies in humans are needed to have a wide spectrum of positive and probable negative effects. The good news is the fact that now is discovered the mechanism and it can be used to get the desired effects!