SAN FRANCISCO-Patients diagnosed with metastatic renal cell carcinoma who continue to smoke significantly reduce their overall survival, researchers reported here at the 2016 Genitourinary Cancers Symposium (Abstract 552).
Even though response to first-line targeted therapies is similar among smokers, non-smokers, and former smokers, those patients who continue to smoke have a median survival that is about eight months shorter than their counterparts who don't smoke, said Jose Ruiz-Morales, MD, a genitourinary fellow at the Tom Baker Cancer Center, University of Calgary, Alberta, Canada.
"This is a teaching moment for our patients," Ruiz-Morales told OT. "Patients who quit smoking returned to a similar risk of death from renal cell carcinoma compared with patients who never smoked. Smoking cessation should be a counseling priority among metastatic renal cell carcinoma patients receiving targeted agents."
Dissecting the Data
Ruiz-Morales and his colleagues scrutinized data from 1,842 patients diagnosed with metastatic renal cell carcinoma treated with targeted therapies through the International Metastatic Renal Cell Carcinoma Database Consortium for eight cancer centers. At baseline assessment, 755 of the patients were former smokers; 795 were never smokers, and 292 were current smokers.
Complete responses to treatment were achieved by 2 percent of the current smokers, 2.2 percent of those patients who never smoked, and 2.4 percent of the former smokers.
Partial responses were achieved by 19.9 percent of the current smokers, 23.6 percent of the non-smokers, and 23.7 percent of the former smokers. Stable disease was achieved by 48.8 percent of the current smokers, 52.1 percent of the non-smokers, and 50.2 percent of the former smokers. The differences between current smokers and those not smoking was not statistically significant (P=0.134).
Similarly, Ruiz-Morales and colleagues reported that median progression-free survival was not statistically significantly different. The median progression-free survival for the non-smokers was 7.7 months; the median progression-free survival for the former smokers was 7.6 months; and the median progression-free survival for the patients who continued to smoke was 6.1 months (P=0.66).
Impact of Treatment
The researchers noted that the treatment effects were similar, but the patients who kept smoking died sooner. The overall survival for the non-smokers with metastatic renal cell carcinoma was 23.7 months compared with 23.1 months for the former smokers (P=0.71), a non-significant difference. But the patients who continued to smoke had a median overall survival of 15.8 months (P=0.001).
The meant that on average, smoking costs patients with metastatic renal cell carcinoma 7.9 months of life compared to non-smokers and 7.3 months of life when compared with former smokers. The researchers reported that each pack-year of cigarette smoking increased the risk of death 1 percent (P=0.039).
'Practice-Changing' Information
The message from the study was clear to Xinhua Zhu, MD, attending physician in Genitourinary Medical Oncology, Northwell Health Cancer Center in Lake Success, New York.
"This study will change my practice," he told OT. "If I have any patients with metastatic renal cell carcinoma, I will counsel them to quit smoking. If these patients continue to smoke, they will have a higher probability of more advanced renal cell carcinoma and shorter survival."
Zhu suggested that based on the study results, "the International Metastatic Renal Cell Carcinoma Database Consortium or the Memorial Sloan-Kettering Cancer Center criteria for metastatic renal cell carcinoma risk stratification may be modified by integrating current smoking status as one of the independent risk factors."
"We know that smoking increased the risk of developing renal cell carcinoma," Ruiz-Morales said. "This study indicates that continuing to smoke reduces the benefit one can get from targeted therapies compared to patients who don't smoke."
Important Differences in the Patient Groups Based on Smoking Habits
* 75 percent of the smokers and former smokers were men, compared with non-smokers-66.9 percent of whom had a smoking history (P<0.012);
* Current smokers were more likely to be diagnosed with hypercalcemia (P=0.004), neutrophilia (P=0.038), and thrombophilia (P=0.002) than patients who were not smoking; and
* There were no differences in sarcomatoid features, number of metastatic sites, or non-clear cell histology in either former or current smokers when compared with non-smokers.