What Is Cancer?

Cancer is the result of cell growth that is out of control. In simple terms, cells become abnormal and grow rapidly, forming extra, unwanted, and potentially destructive tissue. This proliferation of cell growth is called hyperplasia. The abnormality that causes cancer cells results from damaged DNA within cells. This damaged DNA may be inherited or it may result from exposure to an environmental cause such as smoking. In fact, the primary risk factors for head and neck cancer (with the exception of nasopharyngeal cancer) have been identified as tobacco (including smokeless tobacco), heavy alcohol use, poor oral hygiene, and mechanical irritation.¹ One potential problem caused by these abnormal cancer cells is that they can travel to various places in the body, begin to grow and proliferate, and replace normal body cells. This traveling of cells is referred to as metastasis. Metastasis may occur when cancer cells enter the bloodstream or the lymph system and travel to a different part of the body.

Cancer usually forms as a tumor, which technically means a swelling or enlargement, although not all cancers form tumors and not all tumors are cancerous. Some tumors are benign rather than malignant. Different types of cancers grow at different rates, create different problems, and respond to different treatments. One way to conceptualize cancer is as a group of diseases with different symptoms and signs. Symptoms are noticed by a patient and taken as an indication that something is not right in the body. Signs are also indicative of health problems but are more definitive of disease as observed by a physician or other health care professional. Symptoms and signs of cancer may change as the disease changes over time. The specific symptoms and signs depend on the location of the cancer; the size of the tumor; direct impact on any surrounding organs, blood vessels, or nerves; and any metastasis of the cancer. Both general and specific symptoms have been associated as warning signs of cancer. These are summarized in Box 6-1.

Different problems may be encountered depending on the type and location of a cancer. The symptoms listed in Box 6-1 provide general categories of problems that may be encountered. Pain is perhaps the most feared of cancer-related problems. Pain does not result from all cancers, but when it does occur it may be the result of tumor growth or result from the treatments used to eradicate the cancer. Another common problem is fatigue. Like pain, fatigue may result either directly from the cancer or as a side effect of cancer treatment. Box 6-2 summarizes some of the salient characteristics that may be associated with cancer-related fatigue.

Cancers may also contribute to significant weight loss and impaired immune function. These problems are not mutually exclusive because malnutrition also contributes to impaired immune function. Impaired immune function contributes to increased complications, poor wound healing, and opportunistic infections. Together, poor nutrition and impaired immune function may contribute to a less-optimistic outcome for patients with cancer. An estimated 30% to 50% of patients with head/neck cancer demonstrate some degree of malnutrition.² Up to half of patients with head/neck cancer reveal some degree of weight loss when cancer is first diagnosed.^3,4 Average weight loss has been estimated between 5% and 10% of baseline body weight.^4,5 Weight loss may result from reduced ingestion or digestion of food and/or impaired absorption or utilization of nutrients by the body in the presence of adequate food and liquid intake. This latter situation may be complicated by the need for increased caloric intake resulting from increased energy expenditure in some patients with cancer. Thus some patients have a biologic need for more caloric intake, but as a result of poor food and liquid intake, absorption, or utilization they actually have a significantly reduced caloric reservoir. This can become a vicious cycle leading to cachexia. Weight loss may be accompanied by anorexia, nausea and/or constipation, and fatigue. Box 6-3 summarizes some of the more general consequences of malnutrition in patients with head/neck cancer.

Early detection and timely treatment for cancers of the head/neck often are associated with improved outcomes. From that perspective, it is important to facilitate early recognition of the symptoms and signs of cancer and obtain appropriate medical diagnosis early in the course of the disease.

Diagnosis of Cancer

As noted, the initial indications of cancer are often symptoms identified by the patient. These should not be ignored because early detection and prompt treatment lead to a better outcome. Depending on the type and location of cancer, various diagnostic tests may be used. These tests are used to identify the specifics of the cancer and help plan the best possible treatment. Patients with head/neck cancer require careful examination by a multidisciplinary team of health care providers. Such teams may vary but a common core membership might include a head/neck surgeon, radiation oncologist, medical oncologist, dentist, social workers, and rehabilitation specialists. The goal of the team evaluation is to characterize the cancer and develop the best comprehensive treatment approach (including rehabilitation when indicated). The team may use a variety of diagnostic procedures, including radiography, computed tomographic and/or magnetic resonance imaging, endoscopy (including both laryngoscopy and esophagoscopy), biopsy and histopathologic confirmation, and physical examination.

CLINICAL CORNER 6-1

Some cancers are identified early, which is believed to lead to earlier treatment and better outcomes. In my practice, I typically ask patients what the initial signs were that “something was wrong.” The answers vary greatly. Some men report that they felt a small lump (size of a pea) in their neck when shaving. Others have told me that their dentist found a growth during routine dental examination. Still others have reported sore throat, persistent dysphonia, or swallowing difficulties. However, the most unusual report was from an elderly man who indicated that he had trouble keeping his dentures in place. This man has a diagnosis of nasopharyngeal carcinoma (NPC). When I looked into his mouth, the reason for the ill-fitting dentures was obvious (see Figure 6-1, A). Subsequently on endoscopic examination the complete tumor was clearly seen (see Figure 6-1, B). Despite the size and location of this growth, this man reported no difficulties with either nasal breathing or the sense of smell.

Remember that NPC often has no early signs and these tumors may grow large before any overt signs are noted by the patient.

CRITICAL THINKING

1. What other head/neck cancer shares this dubious distinction?

2. How might NPC affect swallowing function?

Surgery

Surgery refers to removal of the cancerous tumor and some of the surrounding healthy tissue, referred to as the margin. Surgery is intended to remove as much of the primary tumor as possible and leave no trace of cancer cells in the margin. However, this is not always possible, and surgery often is combined with radiation therapy and/or chemotherapy. In some cases, more than a single surgery may be required to remove the cancer or restore the anatomic or functional deficit caused by the primary surgery. For example, if the cancer has spread to the lymph nodes in the neck, the lymph nodes will be removed. This is called a lymph node dissection or a neck dissection. In other situations reconstruction may be required. This involves moving tissue from another part of the body to fill a gap created by the cancer resection. A variety of procedures have been described to relocate tissue to the head/neck region. Generally referred to as flaps, these are often named for the location from which the replacement tissue is taken. Therefore a pectoralis major flap would be constructed from tissue obtained from the pectoralis major muscle. Other flaps might include a lateral thigh flap, a radial forearm flap, or similar procedures. Figure 6-2 depicts a pectoralis major flap on the left side. Figure 6-3 shows a flap reconstruction of the floor of the mouth and tongue. In some situations bone tissue may be relocated to reconstruct bony deficits in the mandible, or if a majority of the mandible is removed an implant may be used to replace the missing bone (Figure 6-4). If surgical reconstruction is not feasible, a prosthodontist may be consulted to construct artificial dental or facial parts to fill a space created by the initial surgery. If the primary tumor surgery creates a risk to breathing, a tracheotomy may be performed. If severe swallowing problems are anticipated, a gastrostomy may be performed. Either or both of these procedures may be performed at the time of the primary cancer surgery if the surgical team anticipates airway or swallowing problems as a direct result of the surgery.

Surgery is a primary treatment consideration for all small cancers. Contraindications to surgical removal of a small tumor are the possibility of significant deficits to function (speaking, chewing, swallowing) or cosmetic defects. Advanced cancers often require a combination of surgery and/or radiation or chemotherapy. Various surgical approaches may be used depending on the location and size of the cancerous tumor. Box 6-6 lists some of the more common surgeries associated with head/neck cancer treatment.

Surgery, like other cancer treatments, has a number of side effects that can be problematic for patients. Side effects typically depend on the location and type of surgery. Some of these are temporary and others are more permanent. All side effects have an impact on the patient’s quality of life. Box 6-7 lists some of the more frequent side effects from cancer surgery in the head/neck region. The length of time after surgery was performed is an indicator of the prominent side effects. For example, edema will be pronounced in the acute postoperative period. Edema may be accompanied by pain. As the primary surgical site heals, scarring may reduce movement of anatomic structures spared and in the vicinity of the surgery. In addition, if cranial nerves are damaged during the primary surgery or as a result of postoperative scarring, the patient may sustain motor or sensory deficits from nerve damage.

Radiation Therapy

Radiation therapy uses high-energy x-rays to kill cancer cells. Death of the cancer cells leads to shrinkage of the tumor. Radiation therapy may be used as the primary treatment for small tumors, after surgery to destroy residual small pockets of cancer cells, or before surgery to shrink tumors in the hope of more successful surgical removal with fewer residual deficits. Radiation may be administered in two ways: external-beam radiation and internal radiation. External-beam radiation involves aiming a high-energy radiation beam at the tumor and surrounding tissues. External-beam radiation may be applied on a conventional, once-daily schedule or on an altered fractionation schedule. The latter form of radiation therapy may increase acute toxicity, but late effects are similar between these two techniques.⁷ A newer form of external-beam radiation is known as intensity-modulated radiation therapy. This procedure allows more effective doses of radiation to be delivered to the tumor while hitting less healthy tissue around the tumor. This method is intended to result in fewer side effects. Other recent advances in radiotherapy include radiosensitization (using drugs to make cancer cells more sensitive to radiation) and hyperfractionation (giving radiation in small doses several times per day). In general, treatment strategies leading to a lower dose of radiotherapy or radiotherapy to more confined anatomic regions results in less-severe and more transient dysphagia.^8–10

Internal radiation therapy, often referred to as brachytherapy, involves implanting small pellets or rods containing radioactive material into the cancer or near the cancer site. Patients remain hospitalized during this procedure while the implants remain in place.

Side effects from radiation therapy are common both during treatment (acute toxicity) and after treatment (late effects or late toxicity). Some of these effects are transient and others are persistent. In addition, certain side effects may be latent—that is, they may not appear for a substantial period (in some cases years) after the completion of radiation therapy. Many side effects of radiation therapy to the head/neck region contribute directly to dysphagia and resulting decline in nutritional status. If these occur during treatment, patients may experience interruptions in therapy. Box 6-8 lists several side effects that may occur from radiation therapy to the head/neck region.

Before the initiation of radiation therapy, all patients should undergo a complete dental examination. Damaged or decayed teeth may need to be removed because radiation can cause tooth decay. Also, patients who receive radiation to the anterior neck region are at risk for damage to the thyroid gland, contributing to hypothyroidism. This condition may worsen any feelings of fatigue already experienced by the patient. For these patients, thyroid gland function should be monitored on a regular basis.

Chemotherapy

Chemotherapy refers to the use of drugs to kill cancer cells. These agents are typically very powerful drugs that can cause several unpleasant side effects. Chemotherapy may be administered by mouth, intravenously, by injection into a muscle or under the skin, or by injection directly into the tumor. Chemotherapy may be used to palliate symptoms in patients with incurable disease or as an adjuvant to radiation therapy, surgery, or both. Chemotherapy may be used before or after surgery (and/or radiation therapy). Chemotherapy has been used in combination with radiation therapy to treat certain laryngeal cancers in an attempt to preserve the larynx (avoid a total laryngectomy) and subsequent voice functions. As previously mentioned, certain drugs may be used in combination with radiation therapy as a form of radiosensitization. Although these approaches are promising, many combined therapies are still considered experimental. One negative aspect of combined therapies is the risk of increased severity or a wider range of side effects. For example, large clinical studies reported increased acute toxicity in patients receiving concomitant chemoradiation therapy.¹¹ However, at least one review has concluded that posttreatment swallowing dysfunctions noted in patients receiving concomitant chemoradiation therapy were similar to those seen in patients receiving only radiation therapy.¹² Box 6-9 lists several possible side effects from chemotherapy in the treatment of head/neck cancer. Each patient should be evaluated for the presence of one or more of these possible side effects resulting from primary cancer treatments that may affect swallowing function.

Dysphagia from Surgical Intervention

Surgery for head/neck cancer results in the loss, rearrangement, or reconstruction of structures that are important for swallowing function. A traditional rule for predicting dysphagia after surgery for head/neck cancer is the “50% rule.”^19,20 This “rule,” which seems to result from experiences with oral cancers, suggests that removal of less than 50% of a structure will not result in a significant and permanent swallowing problem. However, this rule has been challenged with the introduction of surgical reconstruction techniques as clinicians report good postoperative swallowing function after surgical flap reconstruction.^21,22 Thus individual patient characteristics should be carefully examined both before and after surgery to identify and manage any resulting swallowing impairments.²³ A general guideline is that the more tissue removed or relocated, the higher the probability for postsurgical dysphagia. Of course, this guideline requires modification when combined modalities are used (radiation therapy and/or chemotherapy in addition to surgery). The following text provides a brief overview of certain dysphagia characteristics that may result from surgery involving various aspects of the swallowing mechanism. Table 6-1 presents a summary of certain surgeries with the associated physiologic impact and anticipated swallow deficit.

Surgery for Oral Cancers

Generally speaking, the oral cavity involves the anterior aspect of the tongue, floor of the mouth, submental structures, the mandible, and the maxilla. Oral surgeries often involve more than a single structure. For example, a mandibulotomy may be required to gain adequate surgical access to tumors in the floor of the mouth or other areas of the oral cavity. In general, surgeries for oral cancers may limit mastication, bolus formulation and containment, and bolus transport from the front to the back of the mouth. Surgeries restricted to the tongue often result in transient dysphagia with good functional outcome; however, this may depend on the extent of the tissue removed and the shape of the reconstructed tongue if flap reconstruction is completed.^24,25 When present, swallowing problems resulting from limited tongue resections involve bolus control and transport difficulties and may be transient.

With more extensive resections involving the tongue and floor of mouth with or without flap reconstruction, dysphagia may be expected for varying periods. Such dysphagia typically involves problems with mastication, bolus control, transport to the posterior oral cavity and, in some cases, airway protection as a result of loss of control of the bolus within the oral cavity.26–28 In addition, pain may result from alterations to the temporomandibular joint. In cases of dramatic resection and reconstruction of the mandible, limitations in the pharyngoesophageal segment may result from reduced upward pull from the hyolaryngeal complex that attaches to the mandible. Conversely, some patients with resection limited to oral structures will have functional pharyngeal aspects in swallowing and will do well if compensations can be used for oral deficits. Video 6-1 on the Evolve site demonstrates functional pharyngeal aspects of swallowing in a patient with significant tongue reconstruction. Contrast liquid is delivered to the pharynx by a small straw connected to a syringe to compensate for limited oral control. Note the increase in residue resulting from thicker materials. Also note the patient’s spontaneous compensations to adjust for limited tongue movement.

Practice Note 6-1

Many devices have been suggested to compensate for reduced oral transit in patients with limited tongue movement as a result of resection or paralysis. Glossectomy spoons have been described but are not always accepted by patients. We treated a patient who had floor of mouth and lingual resection and repair with a microvascular flap. As a result of these surgeries, the patient had reduced lingual movement, impaired ability to contain a liquid bolus in the mouth, and impaired ability to transit a pudding or thicker bolus posteriorly in the mouth. We were able to increase oral intake by placing a “cocktail straw” (small straw) on a syringe so that the patient could place liquid (thin and thick) in the posterior mouth where she could control delivery to the pharynx and swallow without complication. View Video 6-1 on the Evolve site for this text for an example of these types of deficits.

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