Acute porphyria linked to higher risk of primary liver cancer, study finds
Patients with acute porphyria have a higher risk of developing primary liver cancer, according to a Swedish study.
The researchers observed that primary liver cancer was 38 times more likely to occur in patients with acute porphyria than in the general population. This risk was even higher for people with active disease who were over the age of 50 or who had been admitted to hospital for treatment.
According to the researchers, patients who are at an increased risk of developing liver cancer should be monitored closely and regularly, including having ultrasounds from the age of 50.
Symptoms of acute porphyria come on suddenly and can last for several hours to several days. They result from a deficiency in one of the many enzymes involved in the production of heme, a molecule necessary for the transport of oxygen in red blood cells.
When this enzyme is absent and not functioning well, the molecules from which heme is formed – called heme precursors – accumulate in the liver and other tissues and may appear in excess in the blood and be eliminated in urine or stool.
Acute porphyria is linked to an increased risk of primary liver cancer. However, “risk estimates are unclear,” the researchers wrote, as are the specific types of porphyria and other factors that put patients at greatest risk.
To investigate this further, the researchers looked at data from 1,244 patients registered in the Swedish Porphyria Registry, a database that includes all patients who are diagnosed with porphyria in Sweden, from 1987 to 2015. The researchers also included 12,333 patients of different age and sex. -matched individuals from the general study population who served as controls.
There were 1063 (85%) patients with acute intermittent porphyria, the most common type of acute porphyria. Of the remaining patients, 125 (10%) had variegate porphyria and 56 (5%) had hereditary coproporphyria. The patients had a median age of 36 years at inclusion and 654 (53%) were women.
During the study period, 266 (21%) patients were admitted to hospital with porphyria. Elevated urinary levels of porphobilinogen (PBG) – a precursor to heme – were found in 494 (46%) patients with acute intermittent porphyria.
At a median follow-up of 19.5 years, there were a total of 108 new cases of primary liver cancer. The most common type of primary liver cancer was hepatocellular carcinomafollowed by cholangiocarcinoma.
These cases accounted for 6.7% (83 of 1,244) of patients with acute porphyria and 0.2% (25 of 12,333) in the general population. This means that patients with acute porphyria were 38 times more likely to develop primary liver cancer than individuals in the general population.
Next, the researchers looked for factors that could put patients at an increased risk of developing cancer. They found that hospitalized patients had a 90% higher risk of developing primary liver cancer than those who had never been hospitalized with porphyria.
Another risk factor for primary liver cancer was a high level of PBG in the urine. While none of the patients who tested negative for PBG developed primary liver cancer, those with high PBG had a risk of developing cancer that was 61 times higher than the general population. In addition, the higher the PBG level, the higher the risk of developing primary liver cancer.
The median age at diagnosis of primary liver cancer was 71 years in patients with acute porphyria and 74 years in individuals in the general population.
None of the patients developed primary liver cancer before the age of 50. Among 175 patients with acute porphyria over the age of 50 who had elevated levels of PBG in urine and/or had been hospitalized with porphyria, the incidence rate of new cases of primary cancer of the liver amounted to 1.7% per year.
“Patients clinically identified with [acute porphyria] …should be advised to undergo biannual ultrasound monitoring from the age of 50,” the researchers concluded.