Currently, nearly 33% patients of prostate cancer usually relapse after they have been treated through surgery or radiotherapy.
Prostate cancer: Researchers may have found a big breakthrough in prostate cancer treatment! A recent study published in the Lancet Journal has found that a medical imaging technique, called the PSMA PET/CT, could help doctors dealing with prostate cancer patients to tailor the treatments on a case-to-case basis, according to a statement released by Lancet. The study was conducted on 300 patients of prostate cancer in Australia, and although it did not assess whether the new technique of conducting scans affected the survival rate among patients, the team of researchers believes this approach could improve the outcomes of treatments by allowing doctors assess the kind of treatment needed in each individual case.
Background of the study
In an interview with Financial Express Online, the lead researcher Professor Michael Hofman of the Peter MacCallum Cancer Centre in Australia said, “Prostate Specific Membrane Antigen (PSMA) PET/CT was pioneered by the Heidelberg group in Germany, on the background of previous war performed in the USA. We performed our first PSMA-PET/CT at the Peter MacCallum Cancer Centre in the middle of 2014. We noted extraordinary images with high tumour contrast and early experience suggesting superiority to conventional imaging modalities such as CT and bone scanning. We sought to validate this by undertaking a phase 3 multicenter randomised trial, and thanks to funding from the Prostate Cancer Foundation of Australia (PCFA) and Movember, we were able to design and execute the ProPSMA trial.”
Why did the team focus on prostate cancer?
Professor Hofman, talking to Financial Express, said, “Prostate cancer is the leading cause of death in men worldwide. PSMA is overexpressed in prostate cancer tissue. Accordingly, PSMA PET/CT represents a very specific test for imaging in prostate cancer, including prostate cancer spread, wherever it occurs in the body. This is advantageous as other disease processes such as inflammation or benign processes do not pose confusion, which can be the case with conventional scans.”
Moreover, the Lancet statement quoted senior author Professor Declan Murphy as saying that nearly 33% patients of prostate cancer usually relapse after they have been treated through surgery or radiotherapy. He partly attributed this to the fact that the present imaging techniques did not accurately detect the spread of the cancer, leading to some men not getting the additional treatment they needed.
How does the imaging technique work?
Combining two different imaging technologies called positron emission tomography (PET) and computed tomography (CT), the approach was found to produce more accurate images than standard imaging technique, helping in pinpointing the spread of cancer in the patient’s body. In absolute figures, PSMA PET/CT imaging technique was found to be 92% accurate, while the standard imaging technique produced 65% accurate scans.
The imaging technique produces detailed scans of the patient’s body and also detects the levels of PSMA, which is a molecule associated with prostate cancer. The researchers administered a radioactive substance which enabled the detection of PSMA to the patients being studied. The PSMA is a molecule which is found in high levels on the cells with prostate cancer.
After the administration of the radioactive substance, when the patients underwent PSMA PET/CT scan, the CT scan produced the images of the patient’s organs and structures while the PET scan lit up the areas which had the presence of PSMA in high levels, indicating that these areas had prostate cancers.
What were the results of the study?
As many as 300 patients of prostate cancer, who were at the risk of having aggressive disease, were recruited for the study at 10 centres across Australia. They were then randomly assigned to getting conventional CT and bone scans done or getting PSMA PET/CT scans done. After six months, the groups were swapped and underwent scanning the alternative imaging technique.
Through the study, the researchers found that while PET/CT scans were 92% accurate as against 65% accuracy of conventional tests, conventional imaging also failed to detect the spread of cancer in 29 patients, giving out a false negative. This figure stood at six patients in the PSMA PET/CT imaging technique. Moreover, the cases of false positives regarding cancer spread were also significantly lower in PET/CT imaging, standing at two patients as against the conventional imaging, which showed false positives for nine patients.
Ambiguous results were also fewer in PET/CT imaging (7%) as compared to conventional imaging (23%). Moreover, while both the imaging techniques involved exposure to radiation, the dosage in PET/CT technique was less than half of the dosage for conventional imaging technique.
The study also found that when the second round of scanning was conducted, 27% of the patients who had earlier undergone conventional imaging had their treatment plan changed after getting PET/CT scanning done. Meanwhile, only 5% of the patients who initially underwent PET/CT scanning had a change in their treatment plan after undergoing conventional scanning in the second round.
How is the research team following up on the study?
Professor Hofman told Financial Express Online, “The patients in this study continue to be actively followed up. We are interested in the long-term prognostic value in patients where this scan did not demonstrate any evidence of metastatic disease. We will be able to report the results of this in a few years’ time.
We are also undertaking work to evaluate artificial image interpretation of PSMA PET using deep learning techniques. This may assist radiologists and nuclear medicine specialists in interpreting these images.”
According to Professor Hofman, “The ProPSMA study demonstrates that PSMA PET/CT can replace conventional imaging with superior accuracy, consequent management change for patients and lower radiation dose. In order for this test to become widely available, we further need to demonstrate health economic benefits. We hope to demonstrate that this new technology is not only more accurate and effective, but can also save money. We are currently undertaking a detailed health economics and evaluation to determine this.”
The Lancet statement said that the costs for this kind of imaging varied according to the geographical areas.
When will this research materialise into change in treatment?
“The results of this study are having an immediate effect. In Australia, this new technology is already widely available and used by urologists and radiation oncologists in the management of their patients. We hope the results of this study will enable funding and widespread global availability of PSMA PET/CT,” Professor Hofman observed.
What else is Professor Hofman’s team working on?
“In addition to using PSMA as a target for imaging, different types of radioactive molecules can be labelled to PSMA to enable delivery of high doses of radiation to tumours, in order to treat prostate cancer. The main radioactive molecule used for the therapy is Lutetium-177 which emits beta-rays. This is proving to be a highly active novel treatment for prostate with few side effects. We are currently conducting a large randomised trial comparing Lutetium-177 PSMA to cabazitaxel chemotherapy,” Professor Hofman told Financial Express Online.
The researchers have said that since not all the patients underwent the procedure, having to either drop out because they had more than three sites of cancer spread or choosing to drop out voluntarily, the study might lead to overestimation in the sensitivity of the PET/CT imaging technique to detect smaller tumours. However, they believe that since the patients were randomly assigned to groups, the data of their study is robust and concrete, contributing significantly to the improvement of treatment for prostate cancer as it stands today.