In a new thesis from Karolinska Institutet, Hari Vigneswaran studied the blood test called Stockholm3, which is used instead of relying only on prostate-specific antigen (PSA) for prostate cancer detection. This test blood biomarkers, genetic information and clinical data to estimate a man’s risk of prostate cancer. In his thesis, Hari Vigneswaran investigated how well the test works in men from different ethnic backgrounds and whether it performs better than other commonly used screening tools.
Prostate cancer is the most commonly diagnosed cancer in men in many parts of the world, and it is also one of the most paradoxical. Most prostate cancers grow so slowly that they would never have caused harm during a man’s lifetime, while a minority are aggressive and can spread and become fatal. The central challenge in prostate cancer care is therefore not simply to find cancer, but to find the right cancer in the right man at the right time. The goal is to detect dangerous tumours early enough to cure them while sparing men with harmless tumours from anxiety, unnecessary biopsies and treatment side effects that bring no benefit.
What have you done in your studies?
“To answer these questions, I first used statistical matching to show that Stockholm3 was likely to perform well in a diverse American population. I then led SEPTA, a trial involving more than 2,000 men at 17 hospitals in the United States and Canada. The study included large numbers of Asian, Black and Hispanic men. We found that Stockholm3 detected aggressive cancers as reliably as PSA testing, while helping avoid many unnecessary biopsies.
Finally, by following men in the original Stockholm screening trial for nearly nine years, I showed that some men with a low PSA but a high Stockholm3 score had aggressive cancers that later recurred after treatment, cancers that standard PSA testing would have missed. In contrast, men with a high PSA but a low Stockholm3 score rarely experienced recurrence, suggesting a less aggressive form of disease.”
What are the most important results in your thesis?
“Taken together, my work supports the use of risk-based blood testing to make prostate cancer screening fairer, more accurate, and less harmful: finding more of the cancers that matter, in men of all backgrounds, while sparing many men from unnecessary biopsies and treatment for cancers that would never have caused harm.”
Why did you become interested in this topic?
“For more than thirty years, the main tool for early detection has been a blood test that measures PSA. PSA screening saves lives, but it is a blunt instrument: a raised PSA is often caused by harmless prostate enlargement rather than cancer, and some men with dangerous cancers have a low PSA. The fixed PSA cut-off measure decides who should undergo a prostate biopsy. This cut-off misses some aggressive cancers and, at the same time, leads to many unnecessary biopsies and to the detection of many harmless tumours. And as urologists, we know that Black men suffer far higher rates of prostate cancer death, yet are consistently under-represented in medical research, so I wanted to find out whether the Stockholm3 test works as well in other ethnic groups as it does in the Scandinavian population in which it was developed.”
Doctoral thesis
” Prostate cancer risk prediction to improve prostate cancer detection “. Hari Vigneswaran, September 2026.
Facts about doctoral theses
A doctoral thesis is the final written product of a postgraduate education, which in Sweden corresponds to four years of full-time studies. It varies between different disciplines how a doctoral thesis is structured. In the field of medicine, the doctoral student usually collects three to five scientific articles and presents them together with a thesis summary or overview, a so-called ‘kappa’ (literally meaning overcoat in Swedish). After the doctoral student has passed the public defence of the thesis, he or she receives a doctoral degree (also called a PhD), which is the highest possible educational degree in Sweden. Karolinska Institutet has approximately 2,000 active doctoral students and each year approximately 350 doctoral theses are published at our university.
