The authors herein evaluated the natural history of IPNs in a large institutional cohort that underwent radical cystectomy (RC). They retrospectively reviewed their institutional database for patients who underwent RC over a 14 year period (2000-2014) for urothelial carcinoma (UCC) of the bladder and had ≥1 identifiable pulmonary lesion on preoperative staging imaging measuring <2cm in any axis. Patients who were M1 at surgery (9 patients) or had non-urothelial histology (51 patients) were excluded. Cumulative incidence of any lung metastasis and overall survival were estimated. Based on this, they aimed to determine the natural history of these pulmonary lesions and evaluate predictors of subsequent metastatic etiology.
They identified 681 patients undergoing RC during the 14 year period, of which 73 patients with an identifiable preoperative IPN met inclusion criteria. In this subset, 23% were female, 22% were active smokers & 55% former smokers. The median age at surgery was 70 years (range 43-88). 51% received neoadjuvant chemotherapy & 62% of RC were performed using the traditional open approach (vs 38% robotically). Final pathologic staging included 16% pT0N0Mx, 19% pTa/Tis/T1N0Mx, 43% pT2-4N0Mx, & 22% pTanyN+Mx.
Median IPN size was 0.7±0.3cm. At median follow up of 23.5 months (approximately 2 years), the IPNs in 92% (67/73) of patients were clinically benign, with metastatic urothelial cancer confirmed in only 5 patients. A primary lung malignancy was diagnosed in 1 patient. In the IPN cohort, lung metastasis at non-IPN sites were detected in 2 additional patients.
Cumulative incidence of any lung metastasis at 12, 24 & 36 months was 5.9% (95%CI 1.9-13.3%), 7.6% (95%CI 2.8-15.7%), & 13.0% (95%CI 5.4-24.1%), respectively. OS at 12, 24 & 36 months was 75.3% (95%CI 62.3-83.9%), 65.8% (95%CI 53-1-75.9%), & 54.0% (95%CI 39.7-66.2%), respectively. There was no difference in survival based on number of lesions (1 or >1) or size of the largest lesion.
Unfortunately, they did not yet address predictors of progression, which would have been useful in helping to understand which patients should have a higher index of suspicion.
Overall, however, the majority of IPNs in patients who proceeded to RC for UCC of the bladder were stable upon follow-up & rarely represented malignancy. Indeed, the CSS and OS for patients with IPNs were consistent with previously published literature for all RC patients. As such, in appropriately staged UCC patients, IPNs should not be a barrier to proceeding with extirpative surgical therapy as they do not represent metastatic disease for the most part.
Limitations / Discussion Points:
- It was unclear if they excluded all patients with cM1 disease or only patients who were M1 at final pathology. While the presumption would be the latter (as they probably wouldn’t be operating on cM1 disease), it was not specifically delineated in the abstract.
- IPN’s are often much smaller than 2 cm, so it is unclear why the authors chose 2 cm as the cutoff size. Many of the larger lesions are likely considered metastatic deposits.
Co-Authors: Brian McGreen, Albert Lee, Karen Ruth, Elizabeth Plimack, Daniel Geynisman, Matthew Zibelman, Benjamin Ristau, Marc Smaldone, Richard Greenberg, Rosalia Viterbo, David Chen, Robert Uzzo, Alexander Kutikov, Fox Chase Cancer Center, Philadelphia, PA
Written by: Thenappan Chandrasekar, MD, Clinical Fellow, University of Toronto, twitter: @tchandra_uromd at the 18th Annual Meeting of the Society of Urologic Oncology, November 20-December 1, 2017 – Washington, DC