Wednesday, February 5, 2014

Bilateral Wilm's Tumor

Now that the dust has settled on the move to the west coast... back to some reading.

A recent discussion about an infant with bilateral renal masses prompted a review of the COG recommendations and protocols for the management of patients with bilateral Wilm's tumor.

Obviously, the basic impetus behind the special consideration for this group of patients is the the need for preservation of functional renal tissue.  Kids with bilateral WT have several factors that contribute to potential renal failure.  These include  intrinsic disease in predisposed kidneys, loss of functional renal tissue after surgery, and injury from chemo and radiation therapy.

Historically, all pediatric patients with bilateral renal tumors have been found to have Wilm's tumor. This, along with the fact that biopsy upstages patients, increases the risk of local recurrence, and can not effectively rule out anaplasia, contributed to the current COG recommendation to proceed with chemotherapy without tissue biopsy.

Once chemotherapy is started, the pattern of tumor response after 6 and 12 weeks determines whether and how therapy is adjusted.

The COG protocol for bilateral renal masses calls for upfront three drug chemotherapy (no biopsy), with re-imaging in 6 weeks.  If, after 6 weeks, there is good response (>30% decrease in size), and the tumor is now resectable with partial renal preservation, then the surgeon proceeds with nephron sparing surgery.

For patients with partial response, but not enough for nephron sparing surgery after 6 weeks, three drug chemotherapy is continued.  At 12 weeks, all patients undergo operative resection; partial nephrectomy if made possible by further reduction in tumor size, or radical nephrectomy.

If there is no good response, then resection is needed to rule out an anaplastic component (chemotherapy needs to be adjusted) or to make sure this is not a benign lesion (further chemotherapy is unnecessary and surgical resection is curative)

Reference:
COG AREN 0534 Protocol: Treatment for Patients with Bilateral, Multicentric, or 
Bilaterally-Predisposed Unilateral Wilms Tumor



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