Introduction
Cancers of the head and neck region are a heterogeneous group of tumors affecting different areas such as the oral cavity, pharynx (nasopharynx, oropharynx, and hypopharynx), larynx, paranasal sinuses, nasal cavity, thyroid gland, etc. Each of these tumors behaves differently with a varied prognosis requiring a multidisciplinary approach (team of surgical, radiation and medical oncologists) for optimal management.
Local management options include surgery and radiation therapy, used either alone or latter as an adjuvant modality. In the adjuvant setting, the goal of radiation therapy is to prevent local recurrence. Role of radiation therapy has increased tremendously in the past decade, with nearly 60 percent of head and neck cancers requiring radiation therapy. The basic principle of radiation therapy is the maximum dose to the tumor and minimum to the nearby healthy organs. This has been made possible with advances in technology.
Depending on the stage of cancer, different management options are available. Factors which help in decision making can be categorized as patient related (age, associated co-morbidities, performance status, finances), disease-related (site, histology, stage), and treatment-related (cost, side effects). Early stage disease can be managed using a single modality either surgery or radiation therapy. Locally advanced cases especially of the oral cavity, are usually treated with surgery followed by radiation therapy, where surgery removes the gross tumor and radiation therapy further sterilizes the tumor bed, thus minimizing the chances of recurrence. Further evidence has taught us that giving chemotherapy along with radiation therapy in select cases amplifies the effect of radiation, thus enhancing the chances of tumor control.
What Are the Indications for Radiation Therapy and Chemotherapy?
The general indications of radiation therapy in the postoperative setting are guided by principles of increased probability of local recurrence. These indications are:
- Large tumor size (> 2 cm).
- Positive surgical margin.
- High-grade lymphovascular and perineural invasion.
- Nodal involvement.
Concurrent chemotherapy is indicated in a positive margin and extranodal extension. Each of these factors is associated with poor prognosis and requires aggressive combined modality approach.
Sites, where radiation with concurrent chemotherapy forms the definitive treatment and results are equivalent to surgery, are nasopharynx, oropharynx, hypopharynx, and larynx. The advantage of chemoradiation over surgery in these sites is function preservation. Other factors that may influence radiation over surgery are patient choice and morbidity associated with surgery higher than that associated with radiation.
Importance of Treating Nodal Involvement:
Another crucial aspect in the management of head and neck cancers that requires mentioning is the treatment of the nodes. Primary drainage nodes should always be the treatment, and proper knowledge of nodal drainage according to the site is very important. Recent studies have shown the importance of treating nodes prophylactically since survival is inversely related to nodal involvement.
What Are the Radiation Related Side Effects?
Radiation-related side effects can be acute and/or delayed. Factors influencing these side effects can be categorized as patient related (age, associated co-morbidities, performance status), and treatment-related (radiation volume, dose to normal organs, the technique of radiation used, and concurrent chemotherapy). Acute complications are:
- Loss or impairment of the sense of taste.
- Mucositis of the oral cavity and pharynx.
- Decreased saliva secretion.
- Darkening of the skin.
Complications experienced after six months:
- Xerostomia.
- Dental caries.
- Osteoradionecrosis.
- Trismus.
- Laryngeal edema.
- Subcutaneous fibrosis.
What Are the Modern Advancement in Radiotherapy?
Modern radiotherapy techniques, such as intensity-modulated radiotherapy (IMRT) and image-guided radiotherapy (IGRT), can offer precise radiation delivery and reduce the dose to the surrounding normal tissues without compromising the target.
- IMRT is an advanced form of three-dimensional conformal radiotherapy using computer-optimized inverse treatment planning and a computer-controlled multi-leaf collimator.
- IGRT is a revolutionary technique that employs the use of imaging (X-ray or CT scan) to ensure accurate radiation delivery as planning.
With these techniques, the intensity of radiation can be modulated so that a higher radiation dose can be delivered to the targets with a sharply conformal target volume coverage, while at the same time the dose to the surrounding normal tissues is markedly reduced. To give the best results, IGRT is usually combined with IMRT.
In addition to IMRT and IGRT, there are certain other novel radiotherapy techniques. Some of them includes:
- Stereotactic body radiotherapy (advanced form of IGRT).
- Brachytherapy (radiation emitting material placed into the body in the form of capsule or seed).
- Proton therapy (restrict cellular damage within the tumor area).
Conclusion
Head and neck cancers are one of the top three cancers worldwide. Radiation therapy has proved itself to be a valuable component of the management of these cancers, either as an adjunct to surgery, or alone depending upon various factors. There are multiple studies and trials in literature which has proven the equivalence of radiation therapy to surgery with lesser side effects. The invent of various advancement in radiotherapy field is offering promising results for various head and neck cancers.
