Do superior sulcus tumors have a better prognosis than other lung cancer sites?

Abstract

The prognosis and treatment of superior sulcus tumors has created much discussion during the last 20 years. The limited number of patients reported by most series, the particular and dramatic presentation, and the difficulties of a surgical resection are some possible explanations. Indeed, most series present their own persona1 experience either from a surgical or a radiotherapeutic point of view with all the problems and limitations due to patient selection. In most series favoring a combined radiosurgical approach, patients treated with radiation alone serve as a control group to assess the superiority of the radiosurgical treatment; these patients have a very dismal outcome but are not candidates for a resection due to tumor extension or poor general condition; furthermore, few details are given on the radiation technique used (high possibily curative doses or only palliative treatment). Komaki et al. present the experience of one single and large institution covering a short period, ten years, and thus avoid these pitfalls (4). Nevertheless, can we conclude from this study that a tumor arising from the upper upper part of the lung necessarily has a better prognosis or a different behavior than other lung tumors? This tumor should present specific prognostic factors, and a different pattern of metastatic spread or tumor growth. According to the data presented by Komaki et al., as well as other investigators, most of the well-known prognostic factors for lung cancers also apply to superior sulcus tumors: cell type, extension, lymph node involvement, weight loss, performance status, completeness of surgical resection, and radiation dose, fractionation (1, 3, 4, 8, 9, 10). To our knowledge, no data are available in the literature supporting a difference in the growth rate. The following comments are often reported in papers: “the prognosis of this tumor stage by stage is apparently better,” or “despite early extension of superior sulcus tumor to invade adjacent structure, regional lymph node involvement is a rare and late manifestation” (3,5). Once again, the data reported for superior sulcus tumor seem to not support that lymph node involvement is uncommon, as the incidence in Komaki et al. 3 series was as high as 55%, a value very close to the one seen in Rochester’s series with radiation alone (3, 10). Furthermore, the presence of positive hilar, mediastinal or scalene lymph node is associated with a very poor outcome in most series (1, 3, 8). The sites of metastatic spread do not differ significantly from other sites of lung cancers; the brain remains a common first site of metastasis (4). For other T3 lesions, long-term survival also depends on the presence or absence of nodal involvement: the 5year survival rates vary from less than 11% in case of N2 disease to 44% in the absence of any lymph node involvement, values are very close to those reported for superior sulcus tumors (Table 1) (2, 7). If the probability of metastatic spread depends on the developmental time or the duration of tumor growth, then its volume may reflect the growth period. A possible answer may be obtained by simply measuring the tumor volume of T3 or T4 lesions and correlating this value with the outcome to determine a possible difference between superior sulcus localization and other sites. In several studies, rib involvement or vertebral erosion was associated with a worse prognosis. This perhaps reflects either a large tumor extension or patients not treated with a curative intent who were not candidates for a surgical resection or high radiation dose. In fact, the tumor classification in use for lung cancers is mainly based on the extension rather than on the size (7). Indeed, there is often a good correlation between size and extension, except in some specific cases, such as superior sulcus or main stem bronchus tumors, where the extension will often classify the lesions as T3 or T4 even in the presence of very small tumors. Local control has been cited as an important prognostic factor for superior sulcus tumors, another argument often presented in favor of its low propensity to metastatic