Could the grade of the tumour be related to nodal involvement?

We read the article of Hattori et al. [1] with great interest. We thank the authors for this well-designed study. Tumour node metastasis (TNM) staging is important for predicting the recurrence of the tumour and for survival. The authors mentioned that sub-centimetric pure solid nodules with high SUVmax values have a tendency toward lymph node metastasis. Also, the invasiveness of the tumour is declared to be an important determinant of recurrence and survival [2]. In this context, we think that the differentiation degree of the tumour may be a prognostic factor in lung cancer. As a result, we recommend lobectomy for high-grade sub-centimetric nodules. Evaluation of the sub-centimetric nodules with PET scans may be misleading [3]. Too many centres do not perform a PET scan for nodules smaller than 1 cm because of high ratio of false-negative results. So, we think that the invasiveness and the grade of the tumour may be directive for whether to perform limited resection or lobectomy in these nodules. In this context, a histopathological decision is thought to be more reliable than PET scan results. As a final comment, we think that grade of the tumour will be a component in the staging system of lung cancer over time, that is, in oesophageal cancer staging.