By Bahram Robert Oliai, M.D.
In this my last newsletter on making the diagnosis of prostate cancer, I explain the process of reporting cancer.
Gleason Grading
Once the diagnosis of prostate cancer has been established a Gleason Grade should be assigned to each focus of cancer in the case. Created by Donald F. Gleason in 1966 based on a study of Minneapolis area Veterans Administration patients, this architecture-based grading system has stood the test of time like an old Ford F-250 pickup truck, always ready to get the job done when called upon. Recently, the Gleason system was updated slightly, however, it still remains pretty true to its original theme (Fig1.).
In grading prostate cancer we assign one number (1-5) to the predominant pattern (1st number) followed by a second number (1-5) representing the minority pattern and add them for the total score (i.e. 3+4=7). I only report the lowest and highest grade patterns present on biopsy specimens and reserve the use of tertiary patterns only for radical prostatectomy specimens. I never assign a grade less than 3 (score less than 3+3=6) to cancers diagnosed on needle biopsy. Why? Epstein et al. have shown that any grade less than this on core biopsy likely represents an under call (1). A total Gleason score of less than 6 has poor reproducibility even among experts and poor correlation with the grade/score at radical prostatectomy. On core biopsy, one can often not appreciate the peripheral aspect of a carcinomatous focus, which is essential in ruling out infiltration, a key diagnostic finding in Gleason pattern 3 cancer. Finally, scores less than 6 (3+3) on needle biopsy may mislead clinicians into thinking patients have “indolent tumors.”
Gleason pattern 1-2 are considered low grade/well-differentiated carcinomas, Gleason pattern 3 are considered intermediate grade/moderately differentiated carcinomas, and Gleason pattern 4-5 are considered high grade/poorly differentiated carcinomas. As the grade (and score) increase so does the risk of positive margins, extraprostatic extension, and lymph node metastases.
Therefore when I diagnose cancer in a needle biopsy the total score will always be 6-10. Table 1 describes the key findings in Gleason patterns 3,4,5.
Finally, each involved core should include the Gleason score and an estimation of tumor amount (I like to use a percentage of core or tissue involved). Perineural invasion and carcinoma present in adipose tissue (as this is diagnostic of extraprostatic extension on needle biopsy) should be reported if present.
At ProPath, for quality assurance purposes every prostate cancer diagnosis is verified by two pathologists and every malignant diagnosis is called to the submitting physician by one of our pathologists (unless specifically directed otherwise). Because we own our laboratory and are unhampered by outside interference we can provide you with superior processing and turnaround time. Results are generally reported within 24 hours after specimen receipt unless ancillary studies are deemed necessary.
I hope you have found this brief newsletter interesting and informative. For more information or practice on Gleason grading an excellent tutorial is available at: http://162.129.103.34/prostate/
I am always ready to support you in your quest for excellent patient care, please do not hesitate to contact me.
Acknowledgments:
Special thanks to Dr. Jonathan Epstein for providing us with the comparative Gleason Grading figure.
References:
1. Epstein JI, Allsbrook WC, Amin MB, Egevad LL, and the ISUP Grading Committee. The 2005 International Society of Urologic Pathology (ISUP) Consensus Conference on Gleason Grading of Prostate Carcinoma. The American Journal of Surgical Pathology 2005; 29(9): 1228-1242.
Date of last revision: August 2007.