Lip Cancer: Not Uncommon, Often Overlooked

by William Stebbins, MD, and C. William Hanke, MD, MPH
 

Skin cancer is the most common type of cancer in the US.1 Despite increased awareness that it is usually caused by the harmful effects of ultraviolet (UV) light, one in five Americans will develop skin cancer in their lifetime.2 

The lips are a not uncommon, but often overlooked site for nonmelanoma skin cancers (NMSC), including the two most common skin cancers, basal and squamous cell carcinoma (BCC and SCC). Most frequently occurring in fair-skinned males over the age of 50, cancer of the lip comprises approximately 0.6 percent of all cancers in the US.3 Studies have shown that males are 3-13 times more likely to develop lip cancers, likely due to occupation-related sun exposure combined with greater tobacco and alcohol use.4, 5
 

The lower lip is approximately 12 times more likely to be affected, owing to its greater exposure to sunlight. A recent 25-year retrospective study of 2,152 patients with lip cancer revealed that 81 percent occurred on the lower lip, 4 with males predominating by 3 to 1. Large epidemiological studies have shown that up to 95 percent of NMSCs on the lower lip are SCCs.6 

Given their highly visible location, the majority of lip cancers are easily detectable and treatable at an early stage. The most commonly employed treatments include surgery, radiation, and cryotherapy (freezing with liquid nitrogen), with cure rates for early lesions nearing 100 percent.7 Although cancers of the lip have relatively low rates of spread to nearby lymph nodes and distant sites, the relapse rate after treatment can range from 5-35 percent, and the mortality associated with large or recurrent SCC of the lip is as high as 15 percent in some studies.6 Once these cancers spread to local lymph nodes, five-year survival rates decrease to approximately 50 percent.8 

Distribution of Lip Cancers 

To assess incidence and gender associations for lip cancers, we prospectively evaluated 100 consecutive patients visiting our practice. The type of skin cancer, specific location on the lips, and gender of the patient were included in the evaluation. 

Our study population consisted of 51 males and 49 females with a total of 68 SCCs and 32 BCCs. Figure 1 demonstrates the normal anatomy of the lip, while Figure 2 shows the distribution and type of skin cancers among the patients. As in numerous prior studies, the most common location was the lower lip. Also consistent with earlier studies was an overwhelming predominance of SCCs compared to BCCs on the lower lip (50 vs. 5), and a higher proportion of upper lip cancer in females compared to males; 60 percent of upper lip cancers occurred in females vs. 40 percent in males. About 70 percent of these upper lip cancers in women were BCCs. Across both sexes, BCCs accounted for 60 percent of upper lip cancers, compared to only nine percent of lower lip cancers. Finally, while most studies cite a significantly higher ratio of men with lip cancers compared to women, in our study, incidence was virtually 1:1. This is likely due to smaller study numbers and the predominance of patients from the same geographic area, which may not be representative of the general population. 

Risk Factors 

Lip cancer has been associated with smoking, alcohol consumption, and immunosuppression. Emerging data implicate human papillomavirus (HPV) in certain oral cancers, but it has not to date been found to be a major cause of lip cancers. The most important risk factor by far is cumulative UV exposure, which is associated with up to 90 percent of all NMSCs.9 A study of Canadian farmers showed they had a threefold increased risk of lip cancer compared to people with indoor occupations, even after accounting for a history of smoking.10 

Immunosuppressed populations in particular must remain extremely vigilant about lip cancer. Kidney transplant patients have a 30-fold increased risk due to use of immunosuppressive anti-rejection drugs.11 People receiving higher doses of immunosuppressants tend to develop more NMSCs than those on lower doses,12 and patients with HIV also demonstrate higher skin cancer risk.13 Immunocompromised patients, especially those with chronic sun exposure (which further suppresses the immune system), must be monitored closely. 

Treatment of Lip Cancers 

When detected and treated early, lip cancer is almost always curable. However, large or recurrent cancers (possibly resulting from insufficient initial treatment) elevate the risk for local and distant spread. 

For several reasons, including greater conservation of healthy tissue and an extremely high cure rate, Mohs micrographic surgery is commonly used to treat lip tumors. Mohs surgery involves removing thin layers of skin tissue, which are then color-coded, mapped, and microscopically examined. If malignant cells are detected, more tissue from the affected area is removed. This process is repeated until no more cancer can be found. 

Mohs surgery offers the highest cure rate of any treatment modalities for primary or recurrent lip tumors,14 with cure rates of 90-100 percent. In one study of 49 patients with SCC of the lip, the five-year cure rate was 92 percent, compared to 80 percent for (non-Mohs) surgical excision and radiation therapy.14

Tumors often extend beyond what the naked eye can detect, but Mohs surgery, with its use of microscopic examination, allows targeted removal of malignant cells while sparing normal skin. This permits optimum functional and cosmetic results. [See Figure 3.]

  

Prevention of Lip Cancers 

Regular use of photoprotective lip blocks (lip products that contain sunscreen) reduce the risk of lip cancer.15 However, many people remain unaware how important consistent lip protection is. In a study of 299 beachgoers, 94 percent demonstrated a high awareness of the risks of UV damage to the skin in general, but only 69 percent demonstrated a high awareness of risk factors specifically for lip cancer.16 Seventy percent of beachgoers used no lip protection whatsoever, and even among those who otherwise properly applied sunscreen, only 37 percent used any lip protection. 

Furthermore, while photoprotective lip blocks can be effective in reducing UV exposure, most people do not apply them properly. From a practical standpoint, the actual Sun Protection Factors (SPFs, which measure protection against the sun’s UVB rays) provided by lip blocks are almost always lower than the number on the package because the blocks are not applied thickly or frequently enough.17 Additionally, many commercially available photoprotective lip blocks may be poorly absorbed and can be broken down quickly by UV light, losing their effectiveness — two compelling reasons for frequent reapplication.18 

Conclusion 

Despite being exposed to large amounts of UV light, the lips are often overlooked as a potential site for skin cancers. It is critical to exercise careful sun protection through a combination of sun avoidance and shade-seeking; frequent application of a high-SPF lip block; and careful monitoring of skin changes. Any changes to the lip that concern you should be brought to the attention of your physician immediately. 

 

Dr. Stebbins is currently a Mohs micrographic surgery and procedural dermatology fellow under the direction of Dr. C. William Hanke at the Laser & Skin Surgery Center of Indiana and St. Vincent Hospital, Indianapolis, Indiana. 

Dr. Hanke is the Director of the Laser & Skin Surgery Center of Indiana in Carmel, IN, and Senior Vice President of The Skin Cancer Foundation. He was the first physician in the United States to earn triple full professorships in Dermatology, Otolaryngology Head and Neck Surgery, and Pathology and Laboratory Medicine. He is past President of the American Academy of Dermatology, and has served as President of five surgical specialty societies: the American Society for Dermatologic Surgery, American College of Mohs Micrographic Surgery and Cutaneous Oncology, the International Society of Cosmetic Laser Surgeons, International Society for Dermatologic Surgery, and the Association of Academic Dermatologic Surgeons. He has written more than 350 publications including 91 book chapters and 20 books. 
 

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