Glottic and Subglottic Cancers treatment

The treatment of glottic cancer is greatly influenced by the secondary goal of voice preservation. Mobility of the vocal cords is a critical factor in selecting treatment. For small cancers (T1, T2) with mobile vocal cords, radiation therapy alone for cure achieves excellent local control rates (T1, 85% to 95%; T2, 65% to 75%) and overall survival rates similar to those for surgical resection. Voice quality, although often impaired by radiation, is generally better than that following surgical resection. Local control rates are 10% to 15% better with primary surgery, but local recurrences after definitive radiation can often be salvaged by subsequent surgery, and this combined approach results in overall survival figures comparable to those with primary surgery.

Tumor involvement of the anterior commissure or arytenoids has been associated with higher local recurrence rates for radiation alone, but this may have been related to understaging. As with supraglottic cancers, careful clinical tumor staging is necessary since underestimation of tumor extent is common. The "irradiate-and-watch" treatment strategy is predicated on close follow-up in order to detect recurrences when they are still salvageable by surgery. Delay in the diagnosis of recurrent glottic cancers after radiation is more frequent than with supraglottic cancers and often requires total laryngectomy for cure. Thus, unreliable patients or patients who are difficult to examine may be more suitable for primary surgical treatment.

Survival figures in radiotherapy series are comparable to local control figures for surgery, reflecting the effectiveness of surgical salvage and the fact that few patients with early-stage glottic cancer die of their disease.

The 5-year survival rates for T1 lesions range from 80% to 95% with either primary surgery or radiation (Table 90-16). Rates for T2 lesions are generally in the range of 70% to 80%, but these rates are decreased 10% to 15% (local control rates drop 20% to 25%) when the mobility of the vocal cords is impaired or transglottic spread is present. Lesions with impairment due to invasion of muscle behave more like T3 cancers and have a poorer response with radiation alone. Transglottic cancers and those with subglottic extension have higher rates of regional metastases and often require total laryngectomy for cure. In selected patients with these more advanced lesions or impaired vocal cord mobility, extended hemilaryngectomy, or subtotal laryngectomy with resection of a major portion of the cricoid cartilage, can achieve excellent cure rates. Voice quality is poor with these extensive procedures, and chronic aspiration or permanent tracheostomy may result. Additionally, these procedures are technically challenging and experience dependent. However, with proper patient selection, these procedures can be well tolerated.

Management of advanced T3 glottic cancers has historically consisted of total laryngectomy with or without postoperative radiation therapy. While older series show suboptimal control rates (20% to 35%) and survival rates (10% to 50%) for unselected sets of T3 and T4 tumors treated with radiation alone, it is now recognized that with proper selection, radiotherapy control rates for T3 lesions can approach 80%. In patients without regional metastases, local tumor control rates with surgery alone are excellent. Significant increases in local control with the addition of radiation therapy have not been clearly demonstrated. However, in patients with regional metastases, overall prognosis is poor and recurrence in the neck is a major problem when surgery alone is used. Better regional tumor control rates are achieved with the addition of adjuvant radiation therapy. Because rates of occult regional metastases approach 30% in patients with advanced glottic (T3, T4) cancers, elective modified or selective node dissections for staging purposes are recommended when surgery is performed for primary disease. Demonstration of histologically positive nodal metastases has been used as an indication for postoperative radiation. Surgery alone is curative in 50% to 80% of patients without nodal metastases, and this decreases to less than 40% if metastases are present.