Although uncommon, some people with cancer will develop granulomas, the clumps of immune cells that characterize sarcoidosis – and those who do are more likely to have better survival outcomes, a new study reports.
Sarcoidosis is causes due to an overactive immune system and is characterized by the formation of granulomas in body tissues. Prior Research has suggested that people with sarcoidosis are at an increased risk of developing cancer. However, there is little published data on the risk of sarcoidosis in cancer patients.
Now a research team analyzed data from 1,809 cancer patients from two institutions: the University of Miami Hospital, Miami Veterans Affairs Medical Center, in Florida, USA, and Chiba University in Chiba, Japan. Note that this clinical trial (NCT03844698) still enrolls participants; the investigation is expected to run until February 2022.
A total of 133 of the patients analyzed (7.4%) were found to have sarcoidosis-like granulomas on biopsies performed after their cancer diagnosis. A total of 61 patients were male and 72 female; their mean age at identification of granuloma was 64.5 years. The most common cancers in these patients were skin cancer (22.5%) and breast cancer (20.3%), followed by lymph node cancer (12.8%) and prostate cancer (10.5%).
36.1% of the patients were Caucasian, 26.3% Asian, and 23.3% Latino.
Note that statistical analyzes indicated that Japanese patients were significantly less likely to develop granulomas within five years of cancer diagnosis, compared to American patients.
Next, the researchers assessed the relationship between granulomas and patient clinical outcomes, and evaluated two groups of patients. The first group included cancer patients who developed granulomas within three years of their cancer diagnosis; for each person in the first group, the researchers then selected a patient with the same cancer type but no granulomas to serve as a control group.
The mean age at diagnosis of cancer was 57.95 in the control group and 58.37 in the granuloma group. Follow-up took more than five years.
Statistical analyzes indicated that, compared to controls, the individuals with granulomas were 4.6 times more likely to be alive two years after their diagnosis. Similar benefits to survival rates were seen at four, six and ten years after diagnosis. Specifically, at age 10, cancer patients with granulomas were 5.53 times more likely to be alive compared to cancer patients without sarcoid-like immune cells.
In addition, the individuals with such clumps of immune cells were significantly less likely to metastases, which occurs when a tumor spreads from one location and begins to grow into other body parts. Since metastasis is associated with poorer survival outcomes in cancers, this finding complements the survival data found.
Likewise, fewer subjects with sarcoid-like granulomas were treated with chemotherapy or radiation – probably because fewer of them experienced metastasis or more advanced cancer stages to stimulate such treatment.
“The frequency of metastatic cancer was significantly lower in patients with sarcoid-like granulomas than in controls. In addition, [the data] showed a significant survival benefit in people with sarcoid-like granulomas, ”the researchers wrote.
“So finding sarcoid-like granulomas could serve as a prognostic biomarker,” she added.
Subsequent analyzes looking at individual cancer types found no significant association between granulomas and survival, although researchers noted that these results were limited by the relatively small number of patients with a particular type of cancer in the groups analyzed.
Since the immune system can kill cancer cells, the researchers speculated that granulomas may be associated with better outcomes, as they indicate increased immune activity that could limit cancer growth.
“Further investigation of this speculation may lead to new therapeutic agents for cancer immunotherapy,” the team wrote. The researchers also noted that there is a need for further research into granuloma formation in general and in cancer patients in particular.