Characterisation of indeterminate pulmonary nodules in colorectal cancer

Management of indeterminate pulmonary nodules (IPN) in colorectal cancer (CRC) is challenging, with no clear guidance for management. We aimed to study whether certain patient and disease based factors can be used to give guidance about further investigation, treatment and outcome of these lesions.

Data was collected via a 2-year retrospective case-note review of patients discussed at the multi-disciplinary meeting with a confirmed diagnosis of CRC and IPN on CT scan. Further studies were identified by a Pubmed search with no limitations and a review of references within those papers. Pooled analysis was performed where the data was available.

Over the two year period, 539 new cases of CRC were discussed locally. Of these, 28 (5.2%) were found to have IPN. Malignancy was more likely when multiple nodules were detected at presentation (p<0.05). Pooled analysis of a further 7 studies was performed where data was available. This confirmed the significance of multiple nodules in terms of predicting malignancy (p<0.01) and additionally demonstrated the significance of nodal disease (p<0.01).

This study demonstrates the difficulties of determining the nature of IPN using either patient or tumour characteristics. Significant factors appear to be the presence of multiple nodules and nodal disease. In such cases we recommend further imaging at time of detection. If absent, we recommend an interval CT scan at six months.