Prognostic markers
Prognostic markers provide a risk assessment on the outcome of a disease. Since some diseases may not require treatment, prognostic markers are useful in preventing patients from going through pointless, frustrating and sometimes costly treatments. On the other hand, prognostic markers could also give information, which would necessitate that the patient receives instant medical attention. They are required to add information to the known factors such as age, tumour grade and receptor status. In other words, the prognostic markers are used for predicting the outcome of the disease.
For prognostic evaluation of colorectal cancer, the size of the tumour is critical information. Exostoses (Multiple)-Like 3 (EXTL3), which is the receptor, and its counterpart, Regenerating Islet-Derived 1 Alpha (REG1A), are prognostic markers for colorectal cancer recurrence (Froelich W., 2006). Both markers are greatly expressed in patients suffering from colorectal tumours with an increased risk or reappearance. These markers may assist in making choices on controlling colorectal cancers. In comparison to healthy tissue, REG1A is increasingly evident in tumours. The period at which the recurrence happens is related to the amount of expression of REG1A (Froelich W., 2006), suggesting as REG1A rises, the slighter the chance of survival without the disease. Another attribute is seen when REG1A and EXTL3 expression is greater in tumours with peritoneal carcinomatosis (Froelich W., 2006). Therefore, these markers are imperative in determining decisions involving avoidance of the cancer chances of recurrence, and its treatment. From this it is clear that prognostic markers are exclusive in their role compared to diagnostic markers. A diagnostic marker informs the scientist of the presence of the disease, however, prognostic markers that are specific seem to be more useful as they inform scientists of a disease, chance of it occurring again, and its level of severity.
Predictive markers
As a general case, most anticancer therapies are unpredictable. Predictive markers indicate if a certain treatment should be given, what kind of treatment and weighs the advantages. A response to a certain therapy is foreseen by the use of predictive markers. In breast cancer, the predictive markers being used are the progesterone receptor and oestrogen receptor (, et al., 2005), which are used by scientist to determine patients with endocrine sensitive breast cancers and who will confidently respond to hormone therapy. HER-2 (epidermal growth factor receptor) is a young predictive marker to determine patients with metastatic disease for treatment with transtuzumab (antibody) (Slamon DJ., 2001). Depending on the amount of HER-2 expression, the patients are categorised into three different levels and therefore given treatment accordingly. The patient is unlikely to respond to tamoxifen (, et al., 2005) if HER-2 expression is too high. Patients who have HER-2 over expression show highest recurrences. With early and advanced breast cancer, high amounts of HER-2 can be connected with a decreased chance of response to hormone therapy (, et al., 2005). From the results of these markers, one concludes the exact type of treatment to be administered to a patient. The use of predictive markers saves money and conserves time wasted in the use of painstakingly unnecessary treatment for patients on whom it will have no significant effect.
All three markers require a high sensitivity as their results may either come back negative while a patient may truly have the illness or they may falsely come back positive when the patient might not suffer from any ailment. Therefore, it is of great importance to obviate these mistakes by using specific markers, especially when used in screening of large groups such as breast cancer. Generally biological markers must be simple to measure and detect, able to discover cancer at an early phase, recognize patients at an elevated risk and recognition of possible recurrence.
References:
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Froelich W., 2006. REG1A and Its Receptor EXTL3 Are Prognostic Markers for Colorectal Cancer Recurrence. September. pp1. [online] Available from: American association for cancer research. <> [Accessed 28th October 2006].
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Slamon DJ, Leyland-Jones B, Shak, H Fuchs S, Paton V, Bajamonde A, Fleming T, Eirmann W, Wolter J, Pegram M, Baselga J & Norton L., 2001. Use of chemotherapy plus a monoclonal antibody against HER2 for metastatic breast cancer that overexpresses HER2. New Engl J. 344, pp783-729. [online] Available from: Breast cancer research. [Accessed 4th November 2006].
Asadullah Naqvi Word count: 994 (not including title or end references)
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Biomedical Sciences FT
Cellular Pathology
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