Glowing Dye May Help Surgeons Cut Out Prostate Cancer

A fluorescent dye may provide surgeons with a “second pair of eyes” in surgery, helping to remove prostate cancer tumors without damaging healthy tissue.

The study is published in The European Journal of Nuclear Medicine and Molecular Imaging.

Developing precision surgical approaches

Prostate cancer is the most common cancer in men in the UK, with around 52,300 new cases every year. Prostate tumors can be difficult to remove fully and surgery may require removal of the surrounding healthy tissue, which can potentially cause unpleasant side effects.

Surgeons can use both scans and the naked eye to guide areas to remove during surgery, but this approach is not perfect, and cancerous tissue can still be left behind. In a new study, called PROMOTE, was led by researchers from the University of Oxford. The study evaluated the effects of a fluorescent dye used to mark prostate cancer tissue and make it easier to remove.

The marker dye consists of a fluorescent dye combined with a molecule that targets a protein commonly found on prostate cancer cells, known as prostate-specific membrane antigen (PSMA). The targeting molecule – a smaller version of an antibody, termed a “minibody” – ensures it binds only to PSMA-bearing cancer cells and not healthy cells.

Using the dye to tag prostate cancer cells in this way enables surgeons to identify the edges of the tumor and potentially spot cells that have spread from the original tumor into the nearby tissue and lymph nodes. This means that more of the healthy tissue can be preserved and more of the tumor removed, reducing both the risk of the cancer returning and adverse side effects.

Lighting the way

The researchers tested the dye – known as IR800-IAB2M – in 23 men diagnosed with prostate cancer. They received injections of the dye before undergoing robot-assisted prostate removal surgery, where surgeons used an imaging system with a special light to make the marked cancer cells glow.

Multiple patients presented with clusters of cancer cells that had spread from the original tumor, which were identified by the dye and could not be seen with the naked eye, the researchers reported.

“With this technique, we can strip all the cancer away, including the cells that have spread from the tumor, which could give it the chance to come back later,” said Freddie Hamdy, Nuffield Professor of Surgery at the University of Oxford. “It also allows us to preserve as much of the healthy structures around the prostate as we can, to reduce unnecessary life-changing side-effects like incontinence and erectile dysfunction.”

“Prostate surgery is life changing. We want patients to leave the operating theatre knowing that we have done everything possible to eradicate their cancer and give them the best quality of life afterwards. I believe this technique makes that possibility a reality,” Hamdy added.

Though the dye is in the early stages of clinical development, imaging methods to detect it could be integrated into robotic surgical tools, and it may even be adaptable to target other cancers expressing other proteins.

A patient’s story

David Butler, aged 77, was one of the 23 men who took part in the study. He received a shock diagnosis of prostate cancer in 2018 after a chance conversation with his doctor.

“I had several biopsies and scans but one scan – the PSMA PET scan – revealed that the cancer was starting to spread from the prostate,” said Butler. “It was in the lymph nodes, it was in loads of places near to the prostate. That information proved vital to the doctors to get the cancer treated quickly.”

David underwent surgery as part of the study in January 2019 to remove his prostate along with several lymph nodes and other cancerous tissues. He suffered a stroke shortly after surgery due to an unrelated heart condition, but he is now fully recovered five years post-surgery and has been cancer-free ever since.

“I retired early to make the most of life’s pleasures – gardening, playing bowls and walking. Taking part in the PROMOTE study has allowed me to have many more of those pleasures for years to come,” he added.

Additional trials are already underway testing the dye in larger groups of patients. These studies will investigate whether the technique removes more of the tumors and preserves more healthy neighboring tissue compared to existing methods.

“Surgery can effectively cure cancers when they are removed at an early stage,” explained Dr. Iain Foulkes, executive director of research and innovation at Cancer Research UK. “But, in those early stages, it’s near impossible to tell by eye which cancers have spread locally and which have not.”

“We hope that this new technique continues to show promise in future trials,” Foulkes added. “It is exciting that we could soon have access to surgical tools which could reliably eradicate prostate and other cancers and give people longer, healthier lives free from the disease.”

Reference: Hamdy FC, Lamb AD, Tullis IDC, et al. First-in-man study of the PSMA Minibody IR800-IAB2M for molecularly targeted intraoperative fluorescence guidance during radical prostatectomy. Eur J Nucl Med Mol Imaging. doi: 10.1007/s00259-024-06713-x

This article is a rework of a press release issued by the University of Oxford. Material has been edited for length and content.