Pathophysiology

Pathophysiology Study Guide

©2018 of 131 Radiation-Induced Oncogenesis Radiation is another factor that contributes to the development of cancer under certain situations. Radiation, including ultraviolet rays, has the ability to change the chemical composition of DNA in cells and cause cancers. This leads to the development of cancer by inducing pyrimidine dimers in the DNA. Further, mutations in the DNA are induced by Gamma radiation, which promotes malignancies such as leukemia, breast cancer, lung cancer, and thyroid cancer. Chemical-Induced Oncogenesis Chemicals, such as man-made compounds, can also cause cancers. Examples include Aniline dyes (responsible for causing bladder cancer), tobacco (responsible for causing lung cancer), and natural compounds, like aflatoxins, which are responsible for causing liver cancer. Oncogenesis is a multi- stage process in which the normal cells become initiated, then become malignant, and then invasive. These stages are termed as initiation, promotion, and progression respectively. Tumor Markers The substances that denote the presence of cancer in the body are termed tumor markers. These are mostly proteins and are found in the blood or urine of the affected person. However, the presence or absence of tumor markers is not enough to diagnose the presence or absence of cancer in the body, as it may also be possible that tumor markers show normal cells, that is, tumor markers can be high in a person not suffering from cancer. Similarly, it may also be possible that a person is suffering from cancer, but the tumor markers are not elevated. Hence, only a few tumor markers are vital in diagnosing cancer. Prostate-Specific Antigen (PSA) Prostate specific antigen is a commonly used tumor marker that is used by doctors to diagnose prostate cancer in its early phase. Almost one-third of the people with high PSA are likely to suffer from prostate cancer. The higher level of PSA increases the probability of the presence of prostate cancer, which can be detected by biopsy. A PSA level above 4ng/ml shows the presence of cancer, while levels as high as 10ng/ml strongly signify the presence of prostate cancer. However, being a slow progressive cancer among the elderly population, PSA may not always be useful in saving lives. After radiotherapy, as well as curative therapy, it is useful in following up, as the PSA level drops down and becomes close of zero. Higher levels of PSA can also be present among elderly men suffering from larger prostates and benign prostatic hyperplasia. Alpha- Fetoprotein (AFP) Alpha feto-protein (AFP) serum, along with an ultrasound, is useful in diagnosing the presence of liver cancer among people suffering from chronic hepatitis. In the case of hepatocellular carcinoma of the liver, the AFP levels are elevated. This marker is also useful as a follow-up tool after treatment. Moreover, the AFP tumor marker is augmented in cases of various testicular cancers like embryonal Achieve Page 18