As of now, the long-term risks posed by NDMA found in certain valsartan-containing drugs remain somewhat unknown, and the amount of NDMA consumed plays a role in that risk.
Valsartan is off patent and is used as a component of other generic medicines, but not all medicines containing the ingredient are involved in the recent recall.
A ‘non-significant’ increase in cancer risk
The new study involved health data on 5,150 Danish patients who filled a valsartan prescription between 2012 and 2018. The data came from four nationwide registries in Denmark: the Danish Cancer Registry, the National Prescription Registry, the National Patient Register, and the Civil Registration System.
The researchers tracked each patient’s exposure to NDMA contamination based on which valsartan drug products they used, as recorded in the National Prescription Registry. The researchers then compared cancer occurrence among the patients who had been exposed to the NDMA contamination versus those who had not been exposed.
The researchers found that over an average of 4.6 years, exposure to valsartan products potentially contaminated with NDMA showed no association with overall cancer risk compared with exposure to valsartan products unlikely to be contaminated.
When the researchers analyzed associations with specific types of cancer, there were increased risks seen for colorectal and uterine cancer, but those risks were not statistically significant. So the researchers remain uncertain whether there could be risk associated with specific cancer types.
In general, “the estimate for our primary outcome suggests a negligible and statistically non-significant increase in cancer risk of 9%,” the researchers wrote in the study.
The study had some limitations, including that the findings only pertain to short-term early cancer risk after exposure to NDMA, which means that more research is needed to explore long-term total cancer risk. Also, the actual NDMA content of each individual valsartan tablet was not included in the data since such information was not made available.
“At most, our findings suggest that the levels of NDMA exposure achieved through valsartan products do not translate into a substantially increased short term cancer risk. Furthermore, the fact that our study evaluates a potential safety concern holds some implications about how to interpret the results,” the researchers wrote in the study.
‘I don’t think it means that patients are completely out of the woods’
“It provides some modest reassurance for the short-term, but the absence of a signal for cancer excess isn’t really all that surprising to me, because it’s just too soon for something like cancer,” said Michos, who was not involved in the study.
“There hasn’t been long enough follow-up to really see a signal. So while I’m reassured that they didn’t find one, I don’t think it means that patients are completely out of the woods,” she said, adding that she plans to inform her own patients about the new study.
“Now that this study is coming out, I’m going to share it with my patients. I think that many of them are worried, and although this data by no means dispels all fears — because it’s not a long enough follow-up — I think it will give them at least some short-term reassurance,” she said. “While this is concerning, the attributable risk of cancer from this exposure, if any, is anticipated to be very low.”
In the editorial, they noted how the study was planned, conducted, analyzed and published all within three months from when regulatory authorities were notified of the contamination issue.
“This study alone cannot dispel doubts about the potential risk for patients in the longer term, but it helps inform decision making around this episode,” Banzi and Bertele wrote.
“It also illustrates the usefulness of national registries for examining the relations between risk factors and health problems and how research can give a prompt response whenever public health concerns emerge,” they wrote.
All in all, Michos said that the fact a contaminant was found in valsartan to begin with was “a violation of all of our trust.”
“It makes us all wonder about the safety. The public wants their medicines to be safe. So this whole incident raises questions about other products that are made in China, and whether they’re up to standards,” Michos said.
“This contaminant started way back in 2012, so why did it take six years to come to light?” she asked. “Public safety is our number-one priority and so I’m not making light of this at all.”
If you are worried that your drug could be on the recall list, talk with your doctor or pharmacist before changing any routine with your medicine. Because not all valsartan drugs are involved in the recall, they might be able to switch you to a version of the drug made by another company.
If you know your drug is on the recall list, the FDA suggests you continue taking it until your doctor or pharmacist provides a replacement.
News credit : Cnn