We are delighted to present this special issue of ‘Current Opinion in Urology’ addressing several contemporary topics of focal therapy for prostate and kidney cancers.
Over the past two decades, we have observed the changing landscape of prostate cancer and renal tumors. In the era of prostate cancer screening, there has been a stage migration and shift toward small-volume low-to-intermediate-risk prostate cancer . Although radical treatment is still the most common management strategy for localized prostate cancer, its associated comorbidities remain a great concern to patients [2,3]. Active surveillance, on the other end of the spectrum, is the least invasive management strategy for low-risk to some favorable intermediate-risk prostate cancers. However, as many as 20% of patients under active surveillance protocols may ultimately select radical treatment because of disease reclassification and/or patient anxiety [3,4].
In the era of ‘organ conservation’ cancer surgery, focal therapy for prostate cancer offers targeted treatment of the clinically significant cancer foci with preservation of the nonmalignant portion of the prostate gland and genitourinary function. The ‘index lesion theory’ is a fundamental concept of focal therapy. Despite the multifocal nature of prostate cancer, the index lesion defined as the largest lesion with the highest Gleason score, characteristically drives the oncological outcome of the individual's prostate cancer. In fact, concordance between the genomic sequencing of a high-grade cancer focus and metastatic sites suggests that the index lesion can be the primary source of metastasis [5,6].
Similarly, the incidence of primary renal tumors is rising largely because of an increasing use of imaging modalities for the evaluation of unrelated conditions or nonspecific symptoms. This incidental, often asymptomatic diagnosis is associated with a stage migration, such that more than a half of all renal tumors are detected as stage I (i.e. organ confined renal mass of ≤4 cm in the greatest diameter) . Nephron-sparing modalities, ranging from active surveillance to partial nephrectomy, are the cornerstone of management for these small renal masses. Since its introduction over the past 20 years ago, renal ablation modalities, as an established minimally invasive modality for the management of small renal masses, have been evolving considerably. In the absence of level-I evidence comparing partial nephrectomy versus focal therapy for the management of the small renal mass, several retrospective cohorts have demonstrated low complication rates, quick convalescence, excellent preservation of renal function with comparable oncological outcomes to renal focal therapy .
With this landscape in mind and the emerging role of focal therapy as an organ-sparing treatment modality, we invited several experts to share their personal experiences as well as review these hot topics in this field. Notably, our recent knowledge about the prostate cancer index lesion as well as characteristics of the tumor microenvironment, its interaction with tumor growth and progression capabilities were reviewed. In another article, the authors focused on the evolving role of multiparametric MRI (mpMRI) as a noninvasive modality for accurate detection of clinically significant prostate tumors, potentially limiting/avoiding unnecessary biopsies and preventing over-diagnosis in different scenarios. Techniques to correlate mpMRI results with other imaging modalities or with histopathology as the gold standard are presented with an emphasis on the role of multidisciplinary teams and quality assurance initiatives at each user's center or institution. Appropriate case selection, preoperative evaluation for prostate focal therapy, and the role of modern image-based detection of the index lesion were also covered. Oncological and functional outcomes of focal therapy for kidney and prostate cancers, the diagnostic investigations and salvage modalities in men requiring further therapy after initial focal therapy for these cancers are addressed in this edition.
In summary, the past 20 years have been very dynamic, setting the foundation for focal therapy as new concepts along with several technologies have become increasingly integrated to treat patients more precisely. We are confident that the focal therapy concept will continue to play an increasingly leading role in the future.
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Conflicts of interest
There are no conflicts of interest.
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