Differential Relapse Patterns for Non-small Cell Lung Cancer Subtypes Adenocarcinoma and Squamous Cell Carcinoma: Implications for Radiation Oncology

AIMS

Curative-intent (radical) radiotherapy aims to control local disease and cure non-small cell lung cancer (NSCLC). The predominant subtypes of NSCLC are adenocarcinoma and squamous cell carcinoma (SCC). The radiotherapy paradigm offered to patients does not differ according to these two subtypes. Relapse patterns and disease control rates for adenocarcinoma and SCC treated with radical radiotherapy were determined.

MATERIALS AND METHODS

A radical radiotherapy database covering the period from 2004 to June 2016 was examined to determine the first sites of relapse and the actuarial local and distant control rates.

RESULTS

In total, 537 patients with known pathological subtype were treated over the period. In 39 (7%), the site of first relapse was uncertain. Of the remainder, 203 (41%) had adenocarcinoma and 295 (59%) had SCC. At a median follow-up of 16.4 months, 58% had relapsed. There was a difference in relapse patterns (chi-squared test P < 0.0005), with a higher rate of first relapse locally in SCC (42% of all patients versus 24%) and a higher rate of first relapse in the brain for adenocarcinoma (14% versus 3%). The actuarial local control rate was worse for SCC (hazard ratio 0.6, 95% confidence interval 0.5-0.9, P = 0.002). The brain metastasis-free survival was worse for adenocarcinoma (hazard ratio 4.1, 95% confidence interval 2.2-7.5, P < 0.0001).

CONCLUSION

There is a difference in relapse patterns between NSCLC histological subtypes, indicating that these are distinct entities. This may have implications for follow-up policy and strategies to improve disease control.

Playing the odds: lung cancer surveillance after curative surgery

PURPOSE OF REVIEW

After 'curative' resection, many patients are still at risk for further lung cancer, either as a recurrence or a new metachronous primary. In theory, close follow-up should improve survival by catching relapse early - but in reality, many experts feel that surveillance for recurrence is of uncertain value. In this article, we explore the reasons behind the controversy, what the current guidelines recommend, and what future solutions are in development that may ultimately resolve this debate.

RECENT FINDINGS

Although postoperative surveillance for a new lung cancer may impart a survival advantage, this benefit does not appear to extend to the phenomenon of recurrence. Nevertheless, close radiographic follow-up after curative resection is still recommended by most professional societies, with more frequent scanning in the first 2 years, and then annual screening thereafter. Given the radiation risk, however, low-dose and minimal-dose computed tomography options are under investigation, as well as timing scans around expected peaks of recurrence rather than a set schedule.

SUMMARY

Applying the same surveillance algorithm to all lung cancer patients after curative resection may not be cost-effective or reasonable, especially if there is no demonstrable mortality benefit. Therefore, future research should focus on finding safer nonradiographic screening options, such as blood or breath biomarkers, or developing nomograms for predicting which patients will relapse and require closer follow-up. Ultimately, however, better tools for surveillance may be moot until we develop better treatment options for lung cancer recurrence.