Monday, February 4, 2008

"...could the clinical stage be up-graded to reflect a T2 or even T3 classification depending on the imaging results?"


"...when prostate cancer is found prior to biopsy, through the application of newer imaging techniques of the prostate, such as dynamic contrast-enhanced MR imaging and 3D MR spectroscopic imaging, and that prostate cancer is confirmed by subsequent biopsy, would the clinical staging, prior to treatment, still remain T1, or could the clinical stage be up-graded to reflect a T2 or even T3 classification depending on the imaging results?"

... was asked by David, who posted the following comment:


Greetings,

T1c prostate cancer is diagnosed because of an abnormal PSA in the setting of no palpable abnormality on Digital Rectal Examination and the cancer tumor is found in one or both lobes by needle biopsy.

In population screened situations, where a raised PSA is reported, a common clinical staging, utilizing the TNM classification, is T1c, which is tumor identified by needle biopsy. 

However, when prostate cancer is found prior to biopsy, through the application of newer imaging techniques of the prostate, such as dynamic contrast-enhanced MR imaging and 3D MR spectroscopic imaging, and that prostate cancer is confirmed by subsequent biopsy, would the clinical staging, prior to treatment, still remain T1, or could the clinical stage be up-graded to reflect a T2 or even T3 classification depending on the imaging results?

In other words, given that "magnetic imaging is now widely used for staging before treatment and accumulating data indicate the utility of this technique with magnetic resonance spectroscopy in staging and follow-up" , ( Imaging of Prostate Cancer. Oehr P, Bouchelouche K, Curr Opin Oncol. 2007 May;19(3):259-64) can the staging system reflect this improved imaging so as to better delineate T1 from T2 and T3 classification?

Thank you for your expertise,

David



The answer is yes.

Below you find the official and current TNM staging system issued by AJCC 2002 (The American Joint Committee on Cancer (AJCC) TNM staging system for Prostate, 6th edition). 

There it is defined clearly:" T1: Clinically inapparent tumor not palpable nor visible by imaging...Tumor found in 1 or both lobes by needle biopsy, but not palpable or reliably visible by imaging, is classified as T1c."

In other words, if reliably seen on Ultrasound or MRI, the tumor stage changes to T2 or T3, even if the tumor is not palpable (= the tumor is not felt by the urologist during the digital rectal examination).




TNM Definitions

Primary tumor (T)

  • TX: Primary tumor cannot be assessed


  • T0: No evidence of primary tumor


  • T1: Clinically inapparent tumor not palpable nor visible by imaging
    • T1a: Tumor incidental histologic finding in 5% or less of tissue resected
    • T1b: Tumor incidental histologic finding in more than 5% of tissue resected
    • T1c: Tumor identified by needle biopsy (e.g., because of elevated PSA)


  • T2: Tumor confined within prostate*
    • T2a: Tumor involves 50% or less of one lobe
    • T2b: Tumor involves more than 50% of one lobe but not both lobes
    • T2c: Tumor involves both lobes


  • T3: Tumor extends through the prostate capsule**
    • T3a: Extracapsular extension (unilateral or bilateral)
    • T3b: Tumor invades seminal vesicle(s)


  • T4: Tumor is fixed or invades adjacent structures other than seminal vesicles: bladder neck, external sphincter, rectum, levator muscles, and/or pelvic wall


* [Note: Tumor that is found in one or both lobes by needle biopsy but is not palpable or reliably visible by imaging is classified as T1c.]

** [Note: Invasion into the prostatic apex or into (but not beyond) the prostatic capsule is classified as T2 not T3.]

Regional lymph nodes (N)

  • Regional lymph nodes are the nodes of the true pelvis, which essentially are the pelvic nodes below the bifurcation of the common iliac arteries. They include the following groups (laterality does not affect the N classification): pelvic (not otherwise specified [NOS]), hypogastric, obturator, iliac (i.e., internal, external, or NOS), and sacral (lateral, presacral, promontory [e.g., Gerota], or NOS). Distant lymph nodes are outside the confines of the true pelvis. They can be imaged using ultrasound, CT, MRI, or lymphangiography and include: aortic (para-aortic, periaortic, or lumbar), common iliac, inguinal (deep), superficial inguinal (femoral), supraclavicular, cervical, scalene, and retroperitoneal (NOS) nodes. Although enlarged lymph nodes can occasionally be visualized, because of a stage migration associated with PSA screening, very few patients will be found to have nodal disease, so false-positive and false-negative results are common when imaging tests are employed. In lieu of imaging, risk tables are generally used to determine individual patient risk of nodal involvement. Involvement of distant lymph nodes is classified as M1a.
    • NX: Regional lymph nodes were not assessed
    • N0: No regional lymph node metastasis
    • N1: Metastasis in regional lymph node(s)

Distant metastasis (M)*

  • MX: Distant metastasis cannot be assessed (not evaluated by any modality)
  • M0: No distant metastasis
  • M1: Distant metastasis
    • M1a: Nonregional lymph node(s)
    • M1b: Bone(s)
    • M1c: Other site(s) with or without bone disease

* [Note: When more than one site of metastasis is present, the most advanced category (pM1c) is used.]

Histopathologic grade (G)

  • GX: Grade cannot be assessed
  • G1: Well differentiated (slight anaplasia) (Gleason score of 2–4)
  • G2: Moderately differentiated (moderate anaplasia) (Gleason score of 5–6)
  • G3-4: Poorly differentiated or undifferentiated (marked anaplasia) (Gleason score of 7–10)