Second Opinion: Adjunctive Screening & Diagnostic Techniques in Oral Cancer By Lynn W. Solomon, DDS, MS

Second opinions are common in health care; whether a doctor is sorting out a difficult case or a patient is not sure what to do next. In the context of our magazine, the first opinion will always belong to the reader. This feature will allow fellow dentists to share their opinions on various topics, providing you with a “Second Opinion.” Perhaps some of these dentists’ observations will change your mind; while others will solidify your position. In the end, our goal is to create discussion and debate to enrich our profession.

–– Thomas Giacobbi, DDS, FAGD,
Dentaltown Editorial Director

The table below illustrates the five-year relative survival rates in the United States for prostate, cervical, breast and oral cancer. There has been only a nine-percent increase in the five-year survival rate of oral cancer patients from 1950 to 2007. This is an often quoted and disturbing statistic. Superficially, it reflects poorly on the dental profession.

However, I am absolutely certain that not a single one of my dental colleagues has ever deliberately missed an oral cancer. There are multifactorial reasons for this statistic, including: lack of regular dental care for the populations at highest risk for the disease, lack of implementation of tests, lack of insurance coverage for tests as a motivation for patient acceptance, lack of mandatory continuing education in cancer detection for dental professionals and most significantly, a lack of accurate screening tests to allow early detection of premalignant and malignant lesions.

The main reason that survival statistics for prostate, cervical and breast cancers show so much improvement is that screening tools were developed and widely implemented to detect these malignancies in earlier, more treatable stages, e.g. the prostate specific antigen (PSA), PAP smear and mammography tests, respectively. The main reason that survival statistics for oral cancer have improved so little is that there are no screening tests for oral cancer that have been validated in well-designed, randomized, double-blind case controlled studies. The standard methods used today to detect oral cancer, visual examination with incandescent light and manual palpation, are unchanged in the last 57 years.

Although other types of cancer may present in oral and perioral structures, 94 percent of “oral cancers” are squamous cell carcinoma, an epithelial malignancy. As dentists, we are accomplished in diagnosis and treatment of diseases of the teeth and periodontium; however as oral health care providers, it is also our charge to understand and detect the most common cancer of the oral cavity. The challenge for clinicians in visual detection of oral cancer and premalignant lesions (dysplasia and carcinoma in-situ) is the wide variation in clinical appearance, which may present as:

     -Exophytic or fungating, mass forming lesions
     -Endophytic, lesions that form an ulceration
     -Leukoplakia, forming a white plaque
     -Erythroplakia, forming a red patch
     -Erythroleukoplakia, forming a combined red and white patch

Many of these signs may be similar to several other benign oral conditions. To add to the diagnostic challenge, symptoms of oral cancer are generally not apparent until the lesions are in an advanced stage (see Oral Cancer Symptoms in box on left).

Thus, in premalignant and early stages of oral cancer, the patient is unaware of a problem. The wide variation in clinical presentation makes oral cancer detection confusing and subjective.

Oral cancer is a disease where there is a huge difference in the post-treatment patient quality of life. This difference depends on whether the diagnosis was made at an early or late stage. Early invasive lesions of oral squamous cell carcinoma are treated with a limited surgical procedure. Once a tumor has invaded deeper structures and spread to local lymph nodes or distant sites, the patient must undergo a resection, resulting in disfigurement. These patients require grafts or removable prostheses to replace missing tissues. They are treated with radiation and chemotherapy and must deal with sequelae, such as oral mucositis, xerostomia and increased susceptibility to dental caries, and osteoradionecrosis. The five-year survival rate for a localized oral cancer at diagnosis is 61 percent, however the five-year survival rate for an oral tumor with distant metastasis at diagnosis is only 18 percent.

These facts underline the importance of early detection, diagnosis and treatment of oral cancer, which results in a better outcome for the patient. Thus, screening tests for oral cancer are very desirable. Recently, promising new technologies have been introduced to serve as adjuncts to visual examination and manual palpation in detection of oral precancer and cancer.

The science behind the devices listed to the left (under Luminescent Screening Tools on the Market), was adapted from the successful use of similar products in screening for cervical and lung cancer. However, in some respects, the business models of the companies that developed these luminescent screening tools have put the marketing cart before the horse of rigorous scientific proof of efficacy. FDA approval was obtained through a 510(k) exempt FDA device paradigm, which gives a Class I approval, through the reasoning that “a non-invasive device may receive FDA approval if it has been shown to be efficacious in another bodily site.”

The gold standard for oral cancer diagnosis is surgical biopsy and microscopic examination. However, in the area of precancerous epithelial changes, even these results are not unambiguous. There are statistics regarding the likelihood of a mild, moderate or severe epithelial dysplasia to transform into oral cancer, yet in any individual case based on microscopic examination, transformation to a malignancy cannot be predicted.

New technologies have been introduced to serve as preliminary diagnostic tools to evaluate the potential need for a scalpel biopsy to diagnose oral precancer and cancer (listed on the left).

These technologies give us methods to provide a previously unavailable level of examination of suspicious lesions that lays in a place somewhere in between: “Let’s check this in six months,” and “I’m referring you to an oral surgeon for a scalpel biopsy tomorrow.”

Understanding the purpose and significance of a screening or preliminary diagnostic test will prevent misunderstandings of the results on the part of the clinician and the patient. Screening tests are used on persons who are asymptomatic but may have disease precursors or early disease. Generally these tests are painless and have high acceptability levels for patients. Usually they are sensitive, yet rather low on specificity and may have high rates of false positive results.

However, in that event that a screening or preliminary diagnostic technique gives a false positive answer, the worst that will happen is that the patient has a biopsy that is not necessary. At least they have the relief of knowing the lesion is not premalignant or worse. More worrisome is a screening or preliminary diagnostic technique that gives a false negative answer. In that case, clinical judgement must be applied. If a lesion continues to arouse clinical suspicions, the opportunity for a scalpel biopsy has not been lost.

Hopefully, these new screening and preliminary diagnostic technologies will live up to their promise in rigorous research studies of their sensitivity and specificity. In the meantime should we wait to incorporate them into daily practice? My opinion is that we should start using these adjunctive oral cancer screening techniques now. There are several clinical scenarios where adjunctive testing may give information to guide patient management.

In addition, the “wow” factor should not be discounted. It makes an impression on a patient when they have received an extra careful examination with a “special light.” They may take your advice about their smoking or poor dietary habits a bit more seriously when they realize that you are concerned enough to take a liquid cytology sample. The “wow” factor extends to clinicians as well. A busy general dentistry practice may see 3,000 patients / year. In the United States, the yearly incidence of oral cancer is 10 cases per 100,000 persons. Statistically, only one case of invasive squamous cell carcinoma will be discovered in an ordinary practice population in three years. After an early year or two of vigilance, it is human nature to become complacent. Oral exams may become a bit more cursory and the focus of examining radiographs may be the teeth and bone levels, at the expense of analysis of other head and neck structures that are also represented on the image. The addition of an extra screening procedure reinforces the need to be vigilant for oral abnormalities. It also raises patient awareness of oral cancer and the importance of regular dental examinations.

From the 1950s to today, the nine-percent gain in five-year survival statistics for oral squamous cell carcinoma, actually occurred over the last 10 years. Certainly our understanding of oral squamous cell carcinoma and its risk factors, treatment options and prognostic factors has evolved since the 1950s. In addition to the currently available technologies described in this article, even more promising molecular diagnostic technologies are being developed in research labs that will further enhance early disease detection and increase the 59-percent, five-year survival rate for oral cancer. The adjunctive screening and diagnostic technologies available now are not perfect, but they represent a step in the right direction to address the challenges of early detection of oral cancer. Today, it is not necessary to limit detection of premalignant and malignant lesions to visual examination with incandescent light and manual palpation. I challenge my dental colleagues to learn more about adjunctive screening technologies and to consider adding them to the patient examination procedures performed in their offices.

 
Author’s Bio

Dr. Lynn W. Solomon recently joined the faculty of Tufts University School of Dental Medicine in the Department of Oral and Maxillofacial Pathology. She teaches in the pre- and post-doctoral dental programs and practices in Tufts Oral Pathology Services. Her research interest is the autoimmune response to p63 and she has published on a variety of topics in oral pathology.

Dr Solomon is a Diplomate of the American Board of Oral and Maxillofacial Pathology, a fellow of the American Academy of Oral and Maxillofacial Pathology and an alumni member of the dental honor fraternity Omicron Kappa Upsilon. She completed her professional training at the State University of New York at Buffalo School of Dental Medicine.