2010-5-13
Most nasopharyngeal cancers are poorly differentiated, making them highly sensitive to radiation. Additionally, the primary tumor and the regional lymphatic drainage areas of the neck can easily be included within the radiation field. Since the 1940s, China has been conducting deep X-ray radiotherapy for nasopharyngeal cancer. From the 1950s to the 1960s, external beam radiotherapy using 60Co was introduced, gradually shifting from combined large-field irradiation of the nasopharynx and neck to more targeted, smaller-field treatments. This approach not only minimized radiation-related side effects but also significantly improved survival rates. Today, the most effective and reliable method remains treatment with a remote 60Co therapy machine.

1. Indications and Contraindications for Radiotherapy in Nasopharyngeal Cancer
(1) Indications for radical radiotherapy: ① Patients with moderate to good general health; ② No significant bone destruction at the skull base; ③ CT or MRI scans showing no or only mild to moderate infiltration around the nasopharynx; ④ Cervical lymph nodes with a maximum diameter less than 8 cm and still mobile, not yet extending into the supraclavicular fossa; ⑤ No evidence of distant organ metastasis.
(2) Indications for palliative radiotherapy: ① KS score of 60 or higher; ② Patients experiencing severe headaches accompanied by moderate to significant bleeding from the nasopharynx; ③ Individuals with a single distant metastasis or cervical lymph node metastases larger than 10 cm, who, after undergoing palliative radiation therapy, show improvement in general condition and resolution of symptoms, along with controlled distant metastatic lesions—these patients may subsequently transition to definitive (curative) radiotherapy.
(3) Contraindications for radiation therapy: ① KS score below 60; ② Patients with widespread distant metastases; ③ Individuals with acute infectious diseases; ④ Patients suffering from radiation-induced brain or spinal cord injury.
(4) Re-irradiation after recurrence following initial radiotherapy
Principles: Patients with any of the following conditions should not undergo further radiation therapy: ① Recurrence within one year after radiation therapy to the same target area (including both nasopharyngeal and cervical regions); ② Development of radiation-induced encephalopathy or myelopathy following prior radiation treatment; ③ Total treatment duration for the nasopharyngeal target area should not exceed three courses, while the cervical target area should be limited to no more than two courses.
 
2. Selection of Radiation and Irradiation Range
(1) Radiation Field Design: The principle behind designing the radiation field is "small yet comprehensive"—ensuring that all areas affected by the tumor are fully encompassed within the treatment area, while simultaneously protecting normal tissues within the field, especially those highly sensitive to radiation. For the primary nasopharyngeal lesion, bilateral preauricular fields are typically used; however, if the nasal cavity or lateral nasopharyngeal spaces are involved, a frontal nasal field may be added. In cases where the orbit is affected, an upper or lower orbital field can be incorporated. It’s crucial to use lead shields to safeguard the eyes and prevent radiation-induced cataracts. As for the neck, the irradiation range depends on the extent of lymph node involvement. For patients with no palpable cervical lymph nodes, prophylactic irradiation of the bilateral upper neck regions is often recommended. If cervical lymph node metastasis is present, in addition to targeting the known metastatic lesions, preventive irradiation is also applied to the drainage zones below the metastatic sites.
 
3. Radiation Dose and Duration
(1) Continuous radiotherapy: 5 sessions per week, each delivering 200 cGy, for a total dose of 6,000–7,000 cGy over 6–7 weeks.
(2) Fractionated radiotherapy: Typically, radiation therapy is divided into two separate phases, administered five times per week at 200 cGy each session. Each phase lasts approximately 3.5 weeks, with a four-week break between the two phases. The total treatment dose ranges from 6,500 to 7,000 cGy.
 
4. Brachytherapy
(1) Indications:
① Nasopharyngeal localized small lesions (tumor thickness less than 0.5 cm) located on the roof, anterior wall, or lateral wall;
② Residual lesions after external beam radiation therapy or surgical resection for nasopharyngeal carcinoma that meet the criteria outlined in ①
(2) Treatment Approach: Typically, external beam radiation is combined with intracavitary radiation. The external radiation dose ranges from 4,500 to 6,000 cGy, administered over 1 to 2 weeks. This is followed by 1 to 2 sessions of intracavitary radiotherapy, spaced 7 to 10 days apart. For each intracavitary session, the dose is delivered targeting a point 0.25 cm beneath the mucosal surface, with individual doses ranging from 1,000 to 2,000 cGy per session.
 
5. Radiation Reactions and Late Effects, and Their Management
(1) Radiation Therapy Complications
① Systemic reactions may include fatigue, dizziness, decreased appetite, nausea and vomiting, loss of taste or altered taste in the mouth, insomnia, or excessive sleepiness. In some patients, changes in blood counts may occur, particularly a reduction in white blood cells. While these symptoms vary in severity, they can usually be managed with symptomatic treatment. If necessary, vitamins such as B1, B6, and C, along with medications like Metoclopramide, can be administered during radiation therapy. However, if the white blood cell count drops below 3 × 10^9/L, radiation therapy should be temporarily paused.
② Local Reactions: These include reactions in the skin, mucous membranes, and salivary glands. Skin reactions may manifest as either dry dermatitis or moist dermatitis. For mucosal reactions—such as congestion, swelling, exudation, and mucus buildup in the nasopharynx and oropharynx—local application of an anti-inflammatory ointment based on 0.1% borneol-talc powder or lanolin is recommended. Topical mouthwashes and lubricating, anti-inflammatory agents can also be used. In rare cases, patients may experience parotid gland swelling lasting 2–3 days after receiving a single dose of 2 Gy to the parotid gland, followed by gradual resolution. However, when the radiation dose reaches 40 Gy, saliva production significantly decreases, while oral mucosal secretions increase, leading to redness, swelling, and dryness of the mouth. This makes it challenging for patients to consume solid foods. Therefore, excessive irradiation of the parotid gland should be carefully avoided.
(2) Post-radiation syndrome: Key symptoms include temporomandibular joint dysfunction, soft tissue atrophy and fibrosis, radiation-induced dental caries, radiation-related osteoradionecrosis of the jawbone, and radiation-induced encephalomyelopathy. Currently, there is no definitive treatment to reverse these conditions, though symptomatic management and supportive therapies can provide some relief. It’s crucial to strictly avoid overexposure of vital tissues and organs. For more information, please call the Taixinsheng hotline at 010-51571020.