Ductal Adenocarcinoma Of The Prostate: Clinical Features And Implications After Local Therapy

Main Category: Prostate / Prostate Cancer
Also Included In: Urology / Nephrology;  Cancer / Oncology
Article Date: 03 Aug 2009 - 2:00 PDT

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UroToday.com - An unspoken and perhaps forgotten enigma of cancer is its relative drug sensitivity. After all, when treated with cytotoxic agents, a tumor may regress while most normal tissues and organs are either left virtually intact or become eventually healed. Only because a tumor rarely gets into a complete remission, and keeps recurring despite treatment, do we consider cancer generally drug-resistant. Does this dichotomy of drug sensitivity versus resistance allude to a secret about cancer's complex nature and mysterious origin?

An important clinical implication of the stem-cell theory of cancer relates to the role of surgery to overcome drug resistance. Surgery is particularly efficacious for the removal of cancer stem cells that remain locally confined for a prolonged period of time. Whether surgery succeeds in the elimination of drug resistance and the eradication of cancer stem cells depends on the selection of appropriate patients with the right tumor types. Importantly, the theory of a stem-cell origin of cancers provides us with the rationale and offers us some clues of who may be the ideal candidates and what may the right tumors for primary surgery, for metastatectomy, and for neoadjuvant or adjuvant strategies.

Indeed, this is yet another facet to the drug-resistant story. So far, we have focused on the more obvious aspects of drug resistance: dormancy, multi-drug resistance, DNA repair, and apoptosis. Often enough, we have neglected to mention another key aspect of drug resistance: the indolent but intractable differentiated tumor, which behaves just like a normal tissue that is left virtually intact or becomes eventually healed in the face of noxious cytotoxic therapies. Like their respective cancer stem cells, certain differentiated cancer cells are also inherently dormant and multi-drug-resistant; they are more than adept in undergoing DNA repair and avoiding apoptosis. Like a malignant "teratoma," such tumors are invulnerable to the effects of various therapies and need to be extirpated by surgery.

Written by Shi-Ming Tu, MD, et al. as part of Beyond the Abstract on UroToday.com.

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