Surgery to remove a cancerous kidney can often lengthen the lives of patients receiving targeted therapy for metastatic kidney cancer, but only about three in ten such patients undergo the procedure, according to a new study by researchers at Dana-Farber Cancer Institute and Brigham and Women's Hospital.

The study, published by the Journal of Clinical Oncology, also found that patients are more likely to receive the surgery — known as cytoreductive nephrectomy — if they are treated at an academic medical centre, have a smaller tumour, are young, and privately insured.

"Kidney cancer, or renal cell carcinoma, is among the 10 most common cancers in the United States, with more than 60,000 cases diagnosed last year," said the study's senior author, Toni Choueiri, MD, clinical director of the Lank Center for Genitourinary Oncology and director of the Kidney Cancer Center at Dana-Farber Cancer Institute.

"Traditionally, cytoreductive nephrectomy has been part of frontline treatment for the disease. As we've learned about the molecular pathways that drive the disease, drugs that specifically target those pathways have come into wide use. It hasn't been clear whether this has led to a reduction in cytoreductive nephrectomy, whether the procedure improves survival in patients being treated with targeted therapy, and whether some categories of patients are more likely than others to receive the surgery."

Most current guidelines call for cytoreductive nephrectomy to be performed in conjunction with targeted therapy for patients deemed to be good candidates for the procedure.

Studies have shown that patients with poor survival outcomes or with rapidly advancing cancer are less likely to benefit from the surgery.

Using the National Cancer Data Base, a repository of data on patients from 1,500 hospitals nationwide, Choueiri and his associates identified 15,390 patients with metastatic renal cell carcinoma who had been treated with targeted therapies between 2006 and 2013.

Only 5,374 of those patients, or about 35 percent of the total, underwent cytoreductive nephrectomy, the researchers found.

The surgery was associated with longer patient survival.

Patients who underwent the procedure survived for a median period of 17.1 months, the researchers found, compared to 7.7 months for those who didn't receive the surgery.

The investigators also found that patients who were younger, privately insured, treated at an academic medical centre, and had smaller tumours are more likely to have the surgery performed.

It's unclear why the surgery provides a survival benefit for many patients, investigators say, but they theorise that the primary tumour may be especially aggressive and drive metastatic growth elsewhere in the body.

Removing it may therefore slow the spread of the disease.

Future investigations will focus on identifying which patients are most likely to benefit from the surgery.

"The study underscores the importance of careful selection of patients who are good candidates for this surgery," says Maxine Sun, PhD, the co-lead author of the study with Nawar Hanna, MD, her colleague at Dana-Farber and Brigham and Women's.

"As we become better able to identify patients likely to derive the greatest benefit from surgery, survival rates may further improve."

Source: Dana-Farber Cancer Institute