Type of Lymph Node Involvement Influences Survival Rates in T1N1M0 Non-small Cell Lung Carcinoma (Discussion)

In: Lung Carcinoma

17 Sep 2014

Type of Lymph Node Involvement Influences Survival Rates in T1N1M0 Non-small Cell Lung Carcinoma (Discussion)Assigning patients to a particular pTNM subset and stage will allow the most appropriate individual therapeutic decision. The new international staging system developed in 1986 relies heavily on the nodal descriptors Nl, N2, and N3. Lymph node involvement is usually defined as involvement by metastases. However, involvement can also be caused by direct extension complicating the current staging system. In reviewing 57 hospital survivors with pTINlMO disease, it became clear that the type of lymph node involvement related to survival in a statistically highly significant way.

This group of patients taken from a consecutive series of 2,009 patients operated on for bronchial carcinoma between 1977 and 1994 represents a homogeneous group. Overall survival at 5 years was 45.7%, which is compatible with other studies. Survival was not related to histologic features, sex, and type of resection. However, multivariate analysis showed a slighdy significant difference in survival for age: prognosis is worse in patients older than 60 years (p=0.042).

Refining the Nl status, involvement by direct extension is differentiated from involvement by metastases. Moreover, lobar and hilar boundaries were determined, allowing full evaluation and comparison between the two types. Buy Flovent Inhaler

A highly significant difference in survival (p=0.0038) was found between lymph node involvement by direct extension and involvement by metastases. This was supported by multivariate analysis (p=0.0024). When direct extension was compared with hilar node metastases, the significance was even greater (p=0.0006), but this was not found when direct extension was compared with lobar node metastases. Direct extension and lobar metastases may represent a comparable stage of the disease. Maggi et al hypothesize that two-thirds of the malignant cells initially are stopped at lobar lymph nodes and then migrate to the hilar ones.

Survival at 5 years in the group with lobar metastases was better than in the group with hilar metastases, but not significantly (p=0.09). This is probably due to the small size of the lobar group (n=9).

However, when the study population was divided into lobar and hilar disease only, a significant difference in 5-year survival was found both with univariate analysis and multivariate analysis. Yano et al also observed a significant difference between lobar and hilar disease. This is not supported by others who found only a tendency and not a significant trend toward a better prognosis in patients with lobar metastases.

When patients with Nl direct extension are divided into lobar node extension and hilar node extension, no statistical significant difference in survival was observed. Therefore, both hilar and lobar lymph node involvement by direct extension apparently are not comparable with hilar and lobar node metastases, respectively, but the direct extension group, as such, is an entity of its own.

The number of involved nodes and their capsular infiltration have been described to influence survival. The possibility of these factors to influence survival was not investigated in this study.

Recurrence of malignancy was found in 50.9% of all survivors, comparable with previous reports. Local and distant recurrence is less frequent in direct extension disease, whereas no difference was seen between hilar and lobar metastatic disease. The latter was also found by Yano et al. The site of recurrence in Nl disease is controversial; both local and distant tumor growth have been found to be dominant. When in this group of patients, combined recurrence is considered as distant growth, we observe most distant relapses in the hilar group. Retrospectively, in all three groups, patients had occult spread of disease at the date of resection; this was more explicit in both lobar and hilar disease. Autopsy studies confirm that 20 to 36% of postoperative deaths in patients who had potentially curative resections had occult (both local and distant) disease.

Despite being a small group, N1 disease does not seem to be a uniform group. Some argue that N1 disease is an underestimated N2 disease. Significant differences in 5-year survival can be found within stage. The outcome of patients with direct extension (68.6%) is comparable to survival rates of patients with NO disease. Probably, direct extension disease can be seen as early stage, and lobar and hilar metastatic disease as a more advanced stage of the disease. Therefore, in the group with nodal metastases, not only radical resection but also adjuvant therapy should be considered, although until now, the results are variable. It is concluded that 5-year survival after resection of a bronchogenic carcinoma in patients with pTINlMO disease is related to the type of lymph node involvement. Patients with involvement by direct extension have a significantly better prognosis.

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