HPV a Cause of Oral Cancers
Dear OncoLink "Ask The Experts,"
Harry Quon, MD, MS (CRM), Assistant Professor of Radiation Oncology at the Abramson Cancer Center of the University of Pennsylvania, responds:
Thank you for your question.
We now know that carcinomas, that is cancers that come from cells that make up the pink lining in our mouth and throat, can be due to the effects of cancer causing chemicals (or what we call carcinogens) in tobacco or from the effects of viral infections.
The most common type of virus that can cause tumors in the mouth and throat is the human papillomavirus (HPV). The HPV virus has also been shown to cause other types of cancers such as cervical cancer and anal cancer. Studies show that the HPV virus likely is spread to the mouth and throat by way of oral sex.
There are many subtypes of the HPV virus and some are more likely to cause what we call benign tumors and some are more likely to cause cancers. What your sister has appears to be mostly a pre-cancerous tumor. What this means and how does this affect the treatment she needs is described next.
In both cases, the normal "programs" that tell the cell how to behave are affected and allow the cells to keep growing. Normally some of these "programs" tell the cells to die to create a healthy balance. When this is affected, you get lumps of cells that form a tumor. Sometimes the "programs" in the cells become even more affected and not only allow the cells to stay alive longer than they should but to also develop the ability to spread. This is what distinguishes a cancer from a pre-cancerous tumor.
What your sister has, i.e. in situ cancer, is technically a pre-cancer tumor. That is, when the pathologists looked at the tumor under a microscope, there were not any features to tell them it had developed the ability to spread deeper in the voice box. However, one cannot be certain that there may not have been more deeply growing cells that are still left in your sister's voice box. The usual concern is that there may be microscopic cells that are left on the other side of the cut edge from where the tumor was removed. This is why extra treatment is being recommended much like taking out an "insurance policy."
The extra treatments could be with more surgery but this would potentially remove more of the muscles of the voice box and hurt the quality of her voice. Alternatively, radiation treatment has been used because it can treat the deeper muscles of the
voice box and hopefully get rid of any pre-cancer or cancer cells that may be present. The downside with radiation is that your sister is 26 years old and stands a good chance of being cured of this and potentially living 20 years later with the consequences of the radiation treatment. This may include scarring of the voice box and possibly of the swallowing tube behind her voice box. Rarely, the radiation can also cause the development of another cancer in the tissues that received the radiation. While this usually takes 15-20 years to develop and is rare, because of the young age of your sister, this is an important consideration.
One other alternative is the use of photodynamic therapy. This is a form of treatment that has been around for over 30 years and used for the clinical treatment of cancer. The treatment uses certain drugs that can be taken up in the cells of the body, usually more so in cancer or pre-cancer cells, and after some time to ensure that it has been taken up in the cells, the drug is made active by shining a laser light limited to the area that you suspect may have the pre-cancer or cancer cells. The main limitation with this treatment and why it hasn't been as widely adopted is because the laser light in combination with many of these drugs only is active within a few millimeters from the surface of where the light is illuminated.
There are also many technical reasons that we think hasn't been clearly worked out and this is why in some situations, the results have been disappointing.
That said, your sister's voice box likely only needs treatment for a few millimeters and could potentially be an ideal case for photodynamic therapy. The advantage of the photodynamic therapy is that it doesn't have the same risks like radiation therapy in causing second cancers many years later. We can retreat the same area with photodynamic therapy without the risk of seriously injuring the normal tissues. It has limitations but these limitations may actually be advantageous for your sister's situation but should be evaluated by a physician to determine if this is the case.