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Ðề tài: Psa

  1. #1
    mickey
    Guest

    Smile Psa

    Chủ Đề: Smile Psa

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    ►Ngày Gửi: 03-07-09 ►Đánh Giá: Sao

    PSA blood test:


    Introdution:

    With the exception of skin cancer, prostate cancer is the most common type of cancer among men in the United States. Early detection may result from a blood test called a PSA (prostate-specific antigen), and/or a digital rectal exam. The digital rectal exam checks the rear surface of the prostate gland for any abnormalities. A lump or hardness found during the exam might be a sign of prostate cancer.

    I. Definition:

    Prostate-specific antigen (PSA) is a glycoprotein in the cytoplasm of prostatic epithelial cells. It can be detected in the blood of all adult men. The PSA level is increased in men with prostate cancer but can also be increased somewhat in other disorders of the prostate.

    II. Biological function:

    Functions of PSA in the normal prostate and in carcinogenesis.


    The primary biological function of prostate-specific antigen (PSA) is to cleave factors in the semen to aid liquifaction and fertilization (a). In carcinogenesis of the prostate, PSA acts on various molecules to potentially enhance proliferation, cell detachment, invasion and metastasis (b). IGF1, insulin-like growth factor 1; IGFBP, insulin-like growth factor-binding protein; TGF-, transforming growth factor-.

    III. What is the “normal” PSA level?

    A PSA value of >4.0 ug/L has often been defined in the literature as abnormal and is frequently used as a cut-point. However, a man’s PSA level increases steadily as he ages, and some—not all—urologists advocate the use of age-related “normal” PSA cut-points, rather than using >4 ug/L for all. The table below shows suggested age-specific ranges.


    Table Ia. Age-related “normal” PSA cut-points
    Age Range (years) Serum PSA Concentration (ug/L)
    40 – 49-------------------------------<2.5
    50 – 59-------------------------------<3.5
    60 – 69-------------------------------<4.5
    70 - 79 -------------------------------<6.5


    IV. Clinical significance

    According to the Ontario Prostate Specific Antigen (PSA) Clinical Guidelines:
    The use of the PSA test is recommended to monitor patients with established cancer. The PSA test should not be repeated more often than once a month.

    1. Increased levels of PSA may suggest the presence of prostate cancer. However, prostate cancer can also be present in the complete absence of an elevated PSA level, in which case the test result would be a false negative. Obesity has been reported to reduce serum PSA levels.Delayed early detection may partially explain worse outcomes in obese men with early prostate cancer.

    2. The FDA has also approved the use of the PSA test to monitor patients who have a history of prostate cancer to see if the cancer has recurred (come back). If a man’s PSA level begins to rise, it may be the first sign of recurrence. Such a “biochemical relapse” typically precedes clinical signs and symptoms of a relapse by months or years. However, a single elevated PSA measurement in a patient with a history of prostate cancer does not always mean the cancer has come back.

    3. PSA levels can be also increased by prostate infection, irritation, benign prostatic hyperplasia (BPH), and recent ejaculation, producing a false positive result.


    V. Prostate cancer screening

    The U.S. Food and Drug Administration (FDA) has approved the PSA test for annual screening of prostate cancer in men of age 50 and older. PSA levels between 4 and 10 ng/mL (nanograms per milliliter) are considered to be suspicious and should be followed by rectal ultrasound imaging and, if indicated, prostate biopsy. PSA is false positive-prone (7 out of 10 men in this category will still not have prostate cancer) and false negative-prone (2.5 out of 10 men with prostate cancer have no elevation in PSA). Recent reports indicate that refraining from ejaculation 24 hours or more prior to testing will improve test accuracy.

    References:
    1. (PSA) Clinical Guidelines for Testing
    2. nytimes.com
    3. nature.com
    4. wikipedia
    5. The Ontario Prostate Specific Antigen (PSA) Clinical Guidelines
    6. cancer.gov
    7. http://www.health.gov.on.ca/english/...y/summary.html
    thay đổi nội dung bởi: mickey, 03-07-09 lúc 07:43 PM

  2. #2
    mickey
    Guest

    Smile Psa


    1. Anatomy:


    2. Physical Examination



    3. Risk of prostate cancer in two age groups based on Free PSA as % of Total PSA


    4. Screening Recommendations

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