Prostate Cancer Heterogeneity Best Addressed by Combined Biopsy Approach
One of the most highly esteemed institutions in the field of prostate cancer (PCa) diagnosis and treatment is the Johns Hopkins Brady Urological Institute. The opening sentence on one of their website pages plainly states, “No two cases of prostate cancer are alike and correctly diagnosing cancer is critical to developing the best treatment plan.”[i] How to be confident in a correct diagnosis may require a modification of the targeted biopsy approach to rule out genomic variations within the same gland.
In a presentation at the Society of Urologic Oncology Meeting (Washington DC, December 2-4, 2015), Dr. Himisha Beltran (Weill Cornell Medical College, NY) explains the problem of PCa heterogeneity, meaning that cell lines can differ widely at the molecular and cellular levels.[ii] Dr. Beltran’s presentation highlighted the fact that PCa often raises questions that today’s medical science cannot yet answer. Not only do cell lines vary from one patient to another, but some mutations within the same patient may become even more varied.
The source of the problem seems to lie in the multifocal nature of PCa. While about a third of significant PCa tumors are truly unifocal (just one disease site), the question must be asked whether a patient diagnosed with unifocal disease may be harboring latent genetic defects elsewhere in the gland that have the potential to become cancerous. Will a separate tumor eventually develop? Will it be the same cell line as the original tumor? There is not enough information at this time to predict the answer.
Dr. Beltran suggested that “risk stratification may be different dependent on which nodule [tumor] is evaluated… do we need to identify the dominant lesion at diagnosis or do we need to assess multiple or all lesions?” This has implications for clinical practice in terms of biopsy (targeted vs. random sampling).
One approach to obtaining an accurate diagnosis is to combine an MRI-guided in-bore targeted biopsy with additional randomized in-bore sampling. In numerous published studies, in-bore targeted biopsy has clearly demonstrated superior detection of significant PCa over systematic TRUS-guided biopsy. Following a targeted biopsy of the suspicious area with several additional random needles can sample MRI areas that appear negative for PCa. This is the approach taken at the Sperling Prostate Center, which recognizes the possibility of genomic variants in each gland. Qualifying a patient for a focal therapy such as Focal Laser Ablation (FLA) requires an extra measure of caution and clinical responsibility.
The problem of heterogeneity, or diversity, of prostate cancer cells poses many puzzles. However, the progress being made in genomic analysis offers hope that in the not-so-distant future we can unlock the secrets of cancer’s ability to mutate.
[i] Prostate Cancer Diagnosis and Treatment: Advanced Prostate Cancer. http://m.hopkinsmedicine.org/prostatecancer/
[ii] Haseebuddin M. “SUO 2015: Heterogeneity in Prostate Cancer – Session Highlights.” UroToday. http://urotoday.com/suo-2015/suo-2015-prostate-cancer/85170-suo-2015-heterogeneity-in-prostate-cancer-session-highlights.html?utm_source=newsletter_3186&utm_medium=email&utm_campaign=suo-2015-round-up-prostate-cancer
