Lung cancer spread ‘uncommon’ outside of tumour-bearing segment

By Sarah Pritchard, medwireNews Reporter

Lung cancer does not often spread to areas outside of the tumour-bearing segment of the lung when there is no evidence of extrapulmonary nodal metastasis, the tumour is small and peripheral or it has ground glass opacity, study findings show.

Of the 244 lesions from patients who had undergone resection of two or more pulmonary segments for primary lung cancer included in their analysis, intrapulmonary spread was present in 24 (9.8%) cases and included 19 segmental/intersegmental nodal metastases, four parenchymal metastases and one with both.

All cases of intrapulmonary spread were solid tumours, 75% were in the left upper lobe and 75% had multiple nodal mestastases in extrapulmonary nodes.

Only four instances of intrapulmonary spread occurred outside of the tumour-bearing lung segments, at a rate of just 1.6%, the Japanese team of researchers reports in the Annals of Thoracic Surgery.

This type of cancer spread occurred more frequently in cases with extrapulmonary (hilar to mediastinal) nodal metastasis than without, at 7.9% versus 0.5%.

“It is very important to better understand intrapulmonary spread pattern of [non-small-cell lung cancer] because spread to outside of tumor-bearing segment leads to locoregional recurrence in case of segmentectomy”, remark lead researcher Yuichi Sakairi and colleagues from Chiba University Graduate School of Medicine.

“The extrapulmonary node metastasis is searchable at the time of surgery; therefore, this would be a crucial condition for selection of candidates for segmentectomy”, they note. But they recognise the need to determine “the optimal candidacy for limited resection, particularly segmentectomy”.

Their results also revealed that metastasis outside of the tumour-bearing segment did not occur in the 52 peripheral lung tumours measuring 20 mm or less without extrapulmonary nodal metastasis or the 64 tumours of pure or mixed ground glass opacity type.

“[T]herefore such lesions also appear to be good candidates for segmentectomy from the viewpoint of intrapulmonary spread pattern” says the team.

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