SINGAPORE – Due to the closeness of the prostate to the rectum – where cells are delicate and prone to radiation damage – rectal bleeding is one of the more common side effects of radiation treatment for prostate cancer.

Now, some hospitals here are employing a new technique that reduces the risk of such radiation-associated damage by about 50 per cent.

Prostate cancer is the most common form of cancer affecting men in Singapore, with 6,912 cases recorded between 2017 and 2021, according to the Singapore Cancer Registry Annual Report 2021.

Rectal spacers work by acting as a physical barrier between the prostate and the rectum, reducing the radiation dose to the rectum and decreasing the risk of side effects. The spacer is composed of a soft gel that lasts between six months and nine months in the body, after which it naturally dissolves.

It is injected through the perineum – the area between the anus and the scrotum – under ultrasound guidance in a procedure that can typically be done in under 15 minutes, with patients able to return home on the same day.

“The procedure is a minimally invasive outpatient procedure, in hospital, clinic or surgery centre, and typically, patients can go back to normal activities soon after the procedure,” said Associate Professor John Yuen, head and senior consultant at the Singapore General Hospital’s (SGH) department of urology.

Prof Yuen told The Straits Times that among its benefits, the spacer can be seen on computerised tomography or CT scans, reducing the need for magnetic resonance imaging or MRI scans.

SGH and the National Cancer Centre Singapore (NCCS) first used the SpaceOAR rectal spacer, produced by medical device manufacturer Boston Scientific, in 2021.

Since then, 200 patients have benefited from the insertion of the spacer before their prostate cancer treatment.

Clinical Assistant Professor Jeffrey Tuan, senior consultant at the NCCS division of radiation oncology, noted that the technique could also potentially be used to protect organs from radiation when treating other types of cancer.

NCCS and SGH have been designated a regional training centre for SpaceOAR, and will hold its first training workshop in November.

Among those who received the spacer is Mr Raymond Lim, 75, who was diagnosed with Stage 3 prostate cancer in October 2023.

The retiree, who previously worked in the banking sector, underwent the SpaceOAR procedure about two weeks before receiving proton therapy at NCCS in April.

Mr Lim said he experienced no side effects from either the spacer or the therapy, which concluded on May 14.

Dr Arshvin Kesavan, associate consultant at the National University Hospital (NUH) urology department, told reporters on May 20 that between 5 per cent and 10 per cent of patients will not qualify for rectal spacers.

Noting that the procedure requires patients to go under general anaesthesia, Dr Arshvin said for those with heart or lung issues, the risks may outweigh the benefits.

And in cases where the tumour is advanced and growing into the rectum, there may be no place to insert the gel, he added.

NUH, which uses rectal spacers from two companies, has had 150 patients undergo the procedure with no major adverse reactions since introducing the technique in 2022.

The first 120 had “significantly fewer” side effects in the first two years after receiving the procedure compared with those who received radiation treatment without a spacer.

Only five patients had Grade 1 radiation proctitis, a form of inflammation that leads to rectal discomfort, which is usually mild and temporary. In comparison, up to 30 per cent of patients in centres that do not use spacers faced such side effects.

Only one patient had Grade 2 radiation proctitis, referring to rectal bleeding that requires treatment, compared with rates of up to 17 per cent in facilities without spacer use.

“By adopting this technique, we are not just aiming to treat prostate cancer; we are also focused on enhancing the comfort and improving the quality of life for our patients during and after treatment,” said Associate Professor Edmund Chiong, head and senior consultant at the NUH urology department.