Bengaluru: A group of Bengaluru doctors has found that a newer PET scan using a tracer called Fibroblast Activation Protein Inhibitor (FAPI) can detect the spread of ovarian cancer inside the abdomen more accurately than conventional contrast-enhanced CT scans. The prospective study involving 200 women with ovarian cancer has been published in the Journal of Nuclear Medicine.
Peritoneal spread, in which cancer cells spread over the lining of the abdomen, is common in advanced ovarian cancer and can significantly influence whether a patient is considered suitable for surgery. However, small or flat deposits, particularly around the bowel and upper abdomen, can be difficult to detect on conventional imaging. Accurate assessment of the extent of disease is, therefore, important in deciding whether a patient should undergo surgery or receive chemotherapy before surgery.
The study, conducted at Aster International Institute of Oncology, Bengaluru, from May 2024 to April 2025, compared 68Ga-FAPI-04 PET/CT with contrast-enhanced CT in 200 patients before cytoreductive surgery. The researchers compared the scans with what surgeons actually found during surgery, which was taken as the reference standard.
FAPI PET detected peritoneal disease with a sensitivity of 81.8%, compared with 54.6% for CT, while its overall accuracy was 86%, against 78% for CT. CT also tended to underestimate the amount of disease. The average Peritoneal Cancer Index (PCI), a score used to measure the extent of cancer spread inside the abdomen, was 15.7 during surgery, compared with 14.1 on FAPI PET and 10.8 on CT.
Dr Somashekhar SP, one of the doctors involved in the study and group medical director, Aster DM Quality Care, lead consultant in surgical, gynaecological oncology and robotic surgery, Aster Hospitals, Whitefield, said accurately determining the extent of peritoneal disease before surgery can help doctors choose the appropriate treatment strategy.
He said FAPI PET is a relatively new technology in India and is currently available only at a limited number of cancer centres. According to Somashekhar, FAPI PET findings led to a change in treatment decisions in around 18-21% of patients in the study.
Unlike FDG PET, which relies on glucose metabolism and can be affected by normal bowel activity and inflammation, FAPI targets fibroblast activation protein (FAP) found in cancer-associated fibroblasts surrounding tumours. The tracer has low background uptake, making tumour deposits more conspicuous on imaging.
Doctors said the technology could potentially reduce the need for invasive procedures such as diagnostic laparoscopy in some patients by providing a better picture of disease spread before surgery. However, the researchers acknowledged that the study was conducted at a single centre and that further prospective studies are needed.
