Renal cancer for pathologist, 9 September 2017 by Dr Clarence Lei

By Dr Clarence Lei

Renal Cancer, Targetted therapy - what pathologists need to know

Renal cancer is a common; urology units in Malaysia have to deal with a new case almost every week.  It is only curable by surgery.  A close collaboration between the surgeon and pathologist is the cornerstone of management. Input by the pathologist traditionally covers: tumour size, whether malignant, histological tissue type (viz clear cell, papillary & others), Fuhrman nuclear grades (I-IV), necrosis, sarcomatous change, involvement of adjacent structures ie renal capsule, perinephric fat, beyond Gerota’s fascia,  adrenals, lymph nodes (TNM staging), renal vein or IVC emboli or invasion (later is less frequent).  Most nephrectomies nowadays are partial rather than total, ie NSS, nephron sparing surgery, with margins of a few mm. Some “partial nephrectomies” may be part enucleation or seem to have positive margins: the patient side being diathermised.

Features indicating poorer prognosis: large size, invasion of adjacent structures, unfavourable histology, sarcomatous change, venous invasion.  

With increasing use of routine ultrasound, many small renal mass (SRM) are detected. The metatstatic potential is low (1% if SRM < 3cm) and many bigger ones are having Tru-cut biospies done by the radiologist. If the histology report is “benign” (usually oncocytoma) the mass is monitored rather than treated. Biopsy of renal mass used to fraught with difficult histological interpretation and  sampling problems. IHC, immunohistological chemistry may be useful: about 20% of biopsies are benign.

Biopsy now has another role to confirm clear cell carcinoma, which is the renal cancer amenable to the new targetted therapies for metastatic disease eg sunitinib, available in government hospitals. 75% of renal cancers are clear cell carcinoma, and 1/3 of these are metastatic at presentation.  Response rate is good, downstaging tumours & with increase of survival.  Sunitinib is a reference standard for first-line therapy of mRCC in most guidelines, having demonstrated a survival benefit beyond 2 years

The surgeon needs the pathologists’ contribution in the treatment and prognostication of renal cancers.

IAP Malaysian Division                                  17                                     4^th Annual Scientific Meeting 2017