Chapter 091. Benign and Malignant Diseases of the Prostate (Part 5)

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TRUS is the imaging technique most frequently used to assess the primary tumor, but its chief use is directing prostate biopsies, not staging. No TRUS finding consistently indicates cancer with certainty. CT lacks sensitivity and specificity to detect extraprostatic extension and is inferior to MRI in visualization of lymph nodes. In general, MRI performed with an endorectal coil is superior to CT to detect cancer in the prostate and to assess local disease extent. T1-weighted images produce a high signal in the periprostatic fat, periprostatic venous plexus, perivesicular tissues, lymph nodes, and bone marrow. T2-weighted images demonstrate the internal...

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Nội dung Text: Chapter 091. Benign and Malignant Diseases of the Prostate (Part 5)

Chapter 091. Benign and Malignant Diseases of the Prostate (Part 5) TRUS is the imaging technique most frequently used to assess the primary tumor, but its chief use is directing prostate biopsies, not staging. No TRUS finding consistently indicates cancer with certainty. CT lacks sensitivity and specificity to detect extraprostatic extension and is inferior to MRI in visualization of lymph nodes. In general, MRI performed with an endorectal coil is superior to CT to detect cancer in the prostate and to assess local disease extent. T1-weighted images produce a high signal in the periprostatic fat, periprostatic venous plexus, perivesicular tissues, lymph nodes, and bone marrow. T2-weighted images demonstrate the internal architecture of the prostate and seminal vesicles. Most cancers have a low signal, while the normal peripheral zone has a high signal, although the technique lacks sensitivity and specificity. MRI is also useful for the planning of surgery and radiation therapy.
Radionuclide bone scans are used to evaluate spread to osseous sites. This test is sensitive but relatively nonspecific because areas of increased uptake are not always related to metastatic disease. Healing fractures, arthritis, Paget's disease, and other conditions will also cause abnormal uptake. True-positive bone scans are rare if the PSA is
used. The primary outcomes are cancer control and treatment-related morbidities. Definitions of cancer control, however, vary by modality. Often, PSA relapse–free survival is used because an effect on metastatic progression or survival may not be apparent for years. After radical surgery to remove all prostate tissue, PSA should become undetectable in the blood within 4 weeks, based on the PSA half-life in the blood of 3 days. If PSA remains detectable, the patient is considered to have persistent disease. After radiation therapy, in contrast, PSA does not become undetectable because the remaining nonmalignant elements of the gland continue to produce PSA even if all cancer cells have been eliminated. Similarly, cancer control is not well-defined for a patient managed by active surveillance because PSA levels will continue to rise in the absence of therapy. Other outcomes are time to objective progression (local or systemic) and cancer-specific and overall survival; however, these outcomes may take years to assess. The more advanced the disease, the lower the probability of local control and the higher the probability of systemic relapse. More important is that within the categories of T1, T2, and T3 disease are tumors with a range of prognoses. Some T3 tumors are curable with therapy directed solely at the prostate, and some T1 lesions have a high probability of systemic relapse that requires the integration of local and systemic therapy to achieve cure. For T1c tumors in particular, stage alone is inadequate to predict outcome and select treatment; other factors must be considered. Many groups have developed prognostic models that use a
combination of the initial T stage, Gleason score, and baseline PSA. Some use discrete cut points (PSA
not immediate but may develop over time. Of greatest concern to patients are the effects on continence, sexual potency, and bowel function.