Stages of Prostate Cancer
Additional tests that may be used to determine the stage of prostate cancer include:
- Bone scan
- Computed tomography (CT) scan
- Magnetic resonance imaging (MRI) scan
- Lymph node evaluation.
When clinical staging suggests that cancer has spread to the lymph nodes or beyond, radionuclide bone scans can be used to look for metastases to bone, a common site of prostate cancer spread. However, research now shows that patients with PSA levels of 10 ng/mL or less, without bone pain, are so unlikely to have bone metastases -- regardless of tumor stage or grade -- that doctors often recommend that these patients skip the bone scan.
Sophisticated imaging techniques, such as CT and MRI can also help to uncover distant metastases. Like bone scans, however, such tests may be unnecessary for some men. Recent studies indicate that when prostate cancer is clinically localized -- the situation for two-thirds of newly diagnosed cases -- CT and MRI add little to the information available through digital rectal exam, PSA, and TRUS.
Lymph Node Evaluation
When cancer occurs in the prostate, the gland's cells multiply abnormally and may eventually grow through the prostate capsule and invade nearby tissue. It may also spread to the lymph nodes of the pelvis, or it may spread throughout the body through the lymphatic system or the bloodstream.
Carefully removing and examining the lymph nodes -- called pelvic lymph node dissection -- has traditionally been the final check to determine the prostate cancer stage. It may be through "open" surgery or through laparoscopy, using a fiber-optic probe inserted through a small incision in the abdomen (stomach). When PSA level, tumor grade, and stage are evaluated, doctors may choose to bypass pelvic lymph node dissection. However, such clinical decisions may be revised to take into account new findings after surgery (prostatectomy). Pathologic staging judges tissues removed at prostatectomy. The pathologist looks for cancer in outer areas of the gland and at the surgical margins -- the outermost cut edges of the surgical specimen.