Medical Imaging Replaces Biopsy in the Diagnosis of Hepatocellular Carcinoma
Posted Nov 24 2010 12:00am
I believe that radiologists will soon be rendering many more definitive diagnoses than "impressions" in their reports due to improvements in imaging technology. This will place them increasingly in competition with pathologists. A recent report about the diagnosis of hepatocellular carcinoma reinforced this idea in my mind and also presented other interesting facts (see: Imaging Instead of Biopsy for Most Suspected Hepatocellular Carcinomas ). Below is an excerpt from the it:
Although cross-sectional imaging is recommended by several well-respected societies as the standard of care for the diagnosis of hepatocellular carcinoma (HCC), many physicians still rely on a liver biopsy for diagnosis....[A radiologist and expert on this topic recently] discussed the importance of cross-sectional imaging as the diagnostic standard. HCC is currently responsible for more than 650,000 deaths each year worldwide, and is the third most common cause of cancer-related death. "The incidence of HCC is increasing exponentially in the United States because of the increasing prevalence of risk factors such as alcohol consumption, hepatitis B and C, and obesity," he continued. In 2001, the European Association for the Study of Liver guidelines validated imaging as the preferred method of diagnosis of HCC; this recommendation was strengthened by the American Association for the Study of Liver Disease in 2005. "Still, the vast majority of oncologists do biopsies..." [he] said. Biopsies are no more sensitive or specific than imaging, he continued, and biopsy carries about a 3% risk for tumor seeding. Although this is a relatively low risk, when seeding occurs and cancer is found outside the liver, the patient is no longer eligible for transplant. In addition, a needle biopsy can miss a tumor, and pathologists are often unable to differentiate between a high-grade dysplastic nodule and a cancer, [he] continued. "Stromal invasion is hard to detect," he emphasized...."Three different imaging methods are suitable for the diagnosis of HCC: contrast-enhanced ultrasound, which is not used much in the United States because of the widespread availability of the other 2, more sophisticated, methods — computed tomography scanning and magnetic resonance imaging, which is most commonly used. Both of the latter methods are excellent at detecting cancers larger than 2 cm. "According to societal guidelines, a lesion larger than 2 cm with hypervascularity and washout on imaging is diagnostic for HCC," ...."Imaging should be used instead of biopsy to diagnose HCC. There are no downsides to imaging. There is a lot of ignorance out there, and this issue needs to be brought to the attention of the medical community," [he concluded].
First of all, I was unaware that the incidence of HCC was increasing rapidly in the U.S. This does make sense in terms of the three underlying causes of the neoplasm -- alcohol consumption, hepatitis B and C, and obesity. Add this to the growing list of neoplastic complications of obesity (see: Rising Rate of Esophageal Cancer in the U.K.; Relationship to Obesity ). Secondly, it's fascinating that imaging has been recommended by some medical associations as the standard of care for the diagnosis of HCC. This advice was confirmed in another reference I turned up (see: Surveillance and early diagnosis of hepatocellular carcinoma ). Here is the key quote from it:
If the [liver] nodule found during US [ultrasound] surveillance is larger than 1 cm, it should be investigated further with contrast-enhanced dynamic radiological studies, including US, multidetector computed tomography, or magnetic resonance imaging. If the appearance is typical for HCC (i.e., the lesion shows hypervascularization in the arterial phase with washout in the portal venous or the equilibrium phase), biopsy is considered unnecessary and the lesion can be treated as HCC
I am sure that HCC differs in many ways from other malignant neoplasms. However, it's well known that complications may be associated with a biopsy of an internal organ such as the liver. The recommendation that the procedure should be avoided when possible seems sound. It would also be interesting to learn how the figure quoted above of a 3% tumor seeding rate for liver biopsies was established. Nevertheless, it's important to recognize that an important malignant lesion accounting for 650,000 deaths each year worldwide does not now require a biopsy for diagnosis.