Sperling Prostate Center

Can mpMRI Predict Prostate Cancer Stage?

If you are diagnosed with prostate cancer (PCa), you want to know, with as much accuracy as possible:

  • PSA and its variants – determined by blood test
  • Gleason score/Gleason Grade Group – determined by biopsy
  • Clinical stage – determined the old-fashioned way by combination of digital rectal exam or DRE, biopsy, inadequate information from ultrasound, and educated guess

Staging for prostate cancer

According to the American Cancer Society, “A staging system is a standard way for the cancer care team to describe how far a cancer has spread.” Knowing if PCa has begun to spread is crucial, especially for men facing radical prostatectomy (RP). You don’t want to wake up after surgery, not knowing when you’ll pee normally or have erections—only to learn that PCa had already left the gland. If your doctor knew that in advance, would you “look before you leap” with time to modify the treatment strategy?

The standard staging system for PCa is called the TNM system: Tumor (T), Nodes (N), Metastasis (M). While N stage and M stage are definitive for PCa that has escaped the gland, the higher T stages address the possibility of local spread. Clinical T stage is subdivided to describe risk level. Briefly:

  • T1: The tumor is not detectable using conventional DRE or ultrasound.
  • T1a: Incidental discovery in ≤ 5% of tissue, e.g., during a TURP for BPH
  • T1b: Incidental discovery in > 5% of tissue, e.g., during a TURP for BPH
  • T1c: Diagnosed by needle biopsy triggered by rising PSA
  • T2: Diagnosed by needle biopsy, able to be felt during DRE or seen on ultrasound as oddly shaped capsule, but appears confined to the gland
  • T2a: The tumor is present in ≤ one half of the gland
  • T2b: The tumor is present in more than one half but not throughout both sides
  • T2c: The tumor has invaded both sides of the gland
  • T3: The tumor has begun to penetrate the capsule
  • T3a: The tumor has developed outside the prostate but has not spread to the seminal
  • vesicles

  • T3b: The tumor has spread to the seminal vesicles
  • T4: The tumor has spread to neighboring structures, e.g., bladder or rectum, but not nodes

In many RP cases, the exact tumor stage is not known until it is discovered during surgery, or during the pathology analysis of the gland and lymph node analysis after surgery. When the finding indicates a more advanced tumor than first thought, it means the PCa was understaged to begin with. Not good.

3T mpMRI can improve PCa staging

Understaging PCa prior to treatment means that the treatment may not be adequate to control the PCa. No doubt you’ve heard of cases, not just with prostate cancer but with other tumor cancers like breast cancer, in which a surgeon believed he/she had “gotten it all”—only for the crushing news of recurrence a few years later. Perhaps the tumor was understaged from the start. Can 3T mpMRI correct this?

A newly published (Jan. 2021) study out of Germany steers us in the right direction.[i] The title says it all: “Magnetic resonance imaging improves the prediction of tumor staging in localized prostate cancer.” The findings are based on 126 PCa patients from 1/16 – 12/17 who all underwent 3 T multiparametric MRI (mpMRI), had both systematic and MR-targeted biopsies that were positive for PCa, and subsequently had RP as their treatment. MRI identification of probably stage was retrospectively correlated with the final pathology (gland/tissue analysis of the RP specimen after surgery) in order to determine the accuracy of the MRI scans. The scans were analyzed for the following:

✔ Tumor growing beyond the capsule, or measurable extraprostatic extension (EPE) (≥ 3 mm)
✔ Tumor growing within the capsule edge, or length of (pseudo)capsular contact (LCC)
✔ Tumor growing into the neurovascular bundle, or invasion of neurovascular bundle (NVBI)
✔ Tumor at or within the seminal vesicles, or seminal vesicles lesion contact (SVC) or infiltration (SVI).

This table sums up the statistical results:

Stage T2 Stage T3a Stage T3b
76 29 31
MRI predicted no NVBI with 100% accuracy MRI predicted T3a based on LCC with 87% sensitivity and 62% specificity at a length threshold of 12.5mm, and 93% sensitivity and 58% specificity at a length threshold of 11 mm MRI predicted T3b based on SVC in 29/31 cases (positive predictive value 76%, negative predictive value 98%) and 23/31 cases based on SVI (100% positive predictive value, 93% negative predictive value
  MRI predicted T3 based on EPE with 98% positive predictive value, 81% negative predictive value MRI predicted T3 based on EPE with 98% positive predictive value, 81% negative predictive value

After analyzing all data, the study concluded that based on 3T mpMRI, the three independent predictors of stage T3 are extraprostatic extension, length of capsular contact, and seminal vesical contact. The fact that these clinical phenomena are visible to 3T mpMRI tells us that this technology makes it possible to predict stage T3 PCa, allowing doctors and patients to make informed, best-match treatment choices. This is the merit of mpMRI, and this is why our Center is proud to be at the forefront of it.

NOTE: This content is solely for purposes of information and does not substitute for diagnostic or medical advice. Talk to your doctor if you are experiencing pelvic pain, or have any other health concerns or questions of a personal medical nature.

[i] Valentin B, Schimmöller L, Ullrich T, Klingebiel M et al. Magnetic resonance imaging improves the prediction of tumor staging in localized prostate cancer. Abdom Radiol (NY). 2021 Jan 16

 

About Dr. Dan Sperling

Dan Sperling, MD, DABR, is a board certified radiologist who is globally recognized as a leader in multiparametric MRI for the detection and diagnosis of a range of disease conditions. As Medical Director of the Sperling Prostate Center, Sperling Medical Group and Sperling Neurosurgery Associates, he and his team are on the leading edge of significant change in medical practice. He is the co-author of the new patient book Redefining Prostate Cancer, and is a contributing author on over 25 published studies. For more information, contact the Sperling Prostate Center.

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