Oral cancer accounts for 2% of all cancer diagnoses. It’s not common. But for those who are diagnosed, treatment can change the way they look, eat, and speak. And patients with a late diagnosis can face a difficult prognosis.
Oral cancer can appear as an ulcer or as a white or red patch in the mouth that refuses to get better. There are so many challenges to diagnosis, not least because oral cancer is often painless and can go unnoticed. Looking inside the mouth itself can be difficult, being a small space with a moving tongue and sensitive gag reflex.
Diagnosis relies on patients seeing their dentists regularly. Dentists and doctors in general practice must be vigilant and conduct a detailed examination and refer patients early.
How can we make this diagnosis easier? From cutting edge research into cancer blood tests to dyes that can reveal cancerous tissue in the mouth, there are many developments that promise to rapidly improve oral cancer diagnosis. The treatment itself is also advancing. Two recent advances include robotic surgery and sentinel node biopsy, which make surgery less invasive and more accurate.
Better diagnosis of all cancers will improve outcomes across the board. Oral cancer, like all other cancers, has better outcomes the earlier it is diagnosed. Why is it better to find the cancer early? A smaller cancer is easier to cut out. It also is less likely to have spread to other parts of the body. A small surgical procedure can potentially cure the patient. But in oral cancer, chemotherapy treatments unfortunately still aren’t as effective as surgery. Therefore, treating cancer that has spread has much poorer outcomes. Early detection is vital.
Researchers are currently exploring saliva and blood tests that not only can diagnose cancer but also identify aggressive cancers as well as which cancers respond best to different treatments. These include tests for the human papillomavirus, more commonly known as HPV, which has been shown to cause some oral cancers. High levels of other biomarkers can help diagnose the presence of lymph node metastasis or predict long-term survival.
The best treatment for all cancer remains surgery. Removal of all of the cancer before any of it spreads gives patients the best chance of cure. But it’s not that easy. Removing cancer in the mouth means removing part of the tongue, gums or cheek, and other parts of the mouth needed for eating and speech. The more you remove, the better is the chance that you’ve removed all of the cancer, but the patient will have more difficulty with eating, drinking, and speaking afterward.
There is a balance between removing all the cancer and not taking out too much healthy tissue. How does the surgeon know where the cancer stops and the healthy tissue begins? The middle of the cancer is obvious. But the edges can appear normal yet include some invading cancer cells.
Ultimately, you don’t know until the specimen has been seen through a microscope and all the cells are examined for cancer changes. Leaving any cancer cells behind will means they will grow and cause another tumor and possibly spread to the rest of the body.
To help identify the tissue in which cancer has spread, tissue dye is being developed. One such dye known as Lugol solution identifies tissue that has depleted its glycogen stores. Glycogen is the food that cells need to stay alive and grow. The theory is that rapidly growing cancerous tissue will burn through its stored glycogen and therefore show up under this dye.
We are still waiting for the outcome of research to confirm the effectiveness of this dye. Once it is in hand, there is no reason why this dye can’t be used for diagnosis by a dentist. It can even allow pre-cancerous tissue to be removed before it becomes cancer. Marking out cancerous tissue will give surgeons the confidence to remove less tissue without leaving any cancer behind.
Once you’ve found and clearly marked the cancer to be cut out, the other problem is how to get to it. Cancers further back in the mouth can be very difficult to reach and feel. In these hard to reach corners, surgeons may err on the side of taking away more tissue to make sure all the cancer is cut out.
This is where robotic surgery is a game changer. Robots have instruments that are much smaller than human hands. The surgeon can sit at a console and operate these instruments via magnification. Then, the surgeon can precisely remove the cancer tissue only where it was previously difficult to reach or operate on accurately.
Oral cancer treatment often will include surgery to remove lymph nodes in the neck. Known as a neck dissection, this allows the lymph nodes to be examined for the spread of the cancer. Research has shown that radiotherapy will improve outcomes if cancer has spread into the neck.
You can’t identify the presence of cancer in the neck without neck dissection surgery. As with all surgeries, there are risks and complications. Radiotherapy, on the other hand, has side effects including dry mouth, dental decay, and breakdown of jawbones (osteonecrosis).
Sentinel node biopsy has long been used in the treatment of breast cancer to overcome this problem. A chemical is injected into the cancerous tissue and then observed as it drains into the first lymph node in the neck. This first lymph node is then removed and examined.
If this first lymph node doesn’t have any cancer, then it is unlikely that the cancer has spread to the neck. This can save patients with early disease from having a neck dissection. Recent research has shown that sentinel node biopsy is a safe alternative for patients with early stage cancer. It is now included in the cancer treatment guidelines.
These are just a few ways in which ongoing research has improved the way we diagnose and treat oral cancer. With even more advances on the horizon, a future with early cancer detection, minimal surgery, and targeted further treatment is not that far away.
Dr. Chegini is a registrar training to be an oral and maxillofacial surgeon in London. Her role involves looking after patients with both suspected and diagnosed oral cancer. She studied medicine at the University of Oxford and dentistry at King’s College London. Also, this article was written with the assistance of the Oral Cancer Foundation. For more information, visit mouthcancerfoundation.org.