A tumor-specific fluorescent dye and an ultra-sensitive camera system used during surgery can help surgeons identify difficult-to-spot cancers. Surgeons at the University Medical Center, Groningen, the Netherlands, have used this technique for the first time on women with ovarian cancer. This type of cancer is typically difficult to detect early on, and is usually diagnosed at a late stage when prognosis is poor.
When a surgeon is operating on a cancer, he/she should ideally get it right during the first operation. However, tumors may be extremely small and hard to detect. With this new technology, which was created by a Purdue University researcher, the cancer cells literally glow, revealing themselves, so the surgeon can see what needs to be removed.
The surgery, reported in the journal Nature Medicine
, was the first of 10 performed during the first phase of a clinical trial which is assessing the technology. The technology aids surgeons when removing malignant tissue from ovarian cancer patients. Smaller tumors that could easily be missed are lit up, making it easier for the surgeon to spot them and remove them.
Philip Low, from Purdue University, who invented the technology, said surgeons are now able to clearly see clusters of cancer cells just one-tenth of a millimeter wide, compared to the previous 3 millimeters without the technology.
外科医生对有无肿瘤靶向荧光显像剂的卵巢癌细胞的看法。(图片由Gooitzen van Dam提供)[/ h/]
外科医生通常希望使用视觉和触觉观察来发现大约七个肿瘤沉积物。用这种技术形成了34个肿瘤沉积。参与试验的外科医生古伊岑·范·达姆(Gooitzen van Dam)说，这项技术非常符合当前的外科手术实践。
Gooitzen van Dam说:
Low added that chemotherapy or immunotherapy is much more effective when less cancerous tissue remains behind after surgery.
By concentrating on the removal of cancerous tissue, instead of evaluating patient outcome, the researchers were able to considerably reduce how long the clinical trial would take to complete.
Arrangements are underway with the Mayo Clinic for the next phase of the clinical studies.
Low had found that folate can be used like a Trojan horse to surreptitiously introduce an imaging agent or medication into a cancer cell. For ovarian cancer cells to grow and divide, they need large amounts of the vitamin (folic acid). Special receptors on the surface of the cancer cells seize the vitamin, and whatever is attached to it, and pull it inside.
As not all cancer cells express the folate receptor, a test is required to find out whether a patient’s cancer expresses enough of the receptors for the technique to be effective.
At about 85%, ovarian cancer has a very high rate of folate receptor expression. Expression rates for endometrial, kidney and lung cancers are at about 80%, and breast and colon cancers 50%.
Low and team are also looking into how they can target molecules that may be used to carry attached drugs or imaging agents to types of cancer that have no folate receptors.
He plans to develop a red fluorescent dye that can show up through the skin and deep inside the body. He now uses a green dye that has already been approved for patient usage. However, this green dye is not ideal for seeking out cancer cells deep in tissue. Green light has a short wavelength that does not pass through tissue very well, while red has longer a wavelength and does.
Written by Christian Nordqvist