Factors Associated with Grade 3-4 Late Toxicity after Hypofractionated Prostate Salvage Radiation

PURPOSE/OBJECTIVE(S)

We previously reported disease outcomes on patients treated with moderately hypofractionated salvage RT (65-70 Gy in 26-28 fractions using imaging guided IMRT) with >13 years of follow-up. The rate of all late surgical/radiation/disease related grade 3-5 toxicities was 27%, which were documented at a median of 8.7 years after the end of radiation. Here we performed an analysis to attempt to identify factors associated with these toxicities.

MATERIALS/METHODS

A total of 161 patients were analyzed; 44 patients experienced 58 late grade ≥3 toxicities. These were analyzed in several groups which included: all (n = 44), GU (n = 40), GU excluding incontinence (n = 35), stricture/fistula related (n = 28), hematuria related (n = 7), and grade 4 stricture/fistula related (n = 8). We investigated patient factors (age, preRT IPSS), surgical factors (clip volume, approach, margin status), and disease factors (stage, Gleason group, PSA nadir, preRT PSA, surgery to RT time). Surgical clip volume was contoured on CT and recorded in cc. Significance was determined using Mann-Whitney U test for continuous variables and Fisher's Exact test for binary variables.

RESULTS

A higher volume of surgical clips in the prostate fossa was found to be significantly related to eventual grade ≥3 stricture/fistula related event (p = 0.05). The mean surgical clip volume was found to be 2.30 cc in those with a documented grade ≥3 stricture/fistula compared to 1.23 cc in those without. Patients with a positive margin had a 30.0% rate of grade ≥3 GU toxicity compared to 16.2% in those with a negative margin (p = 0.03). Surgical clip volume was not found to be significantly related to pathologic stage, nor to eventual biochemical failure (p = 0.799/0.897). A positive margin was associated with a lower rate of biochemical failure after salvage (p = 0.04). Grade 3 events were documented at a median of 7.7 years and grade 4 events at 12.0 years after the end of radiation.

CONCLUSION

Our previous study found a high rate of grade ≥3 toxicities at time points for which there is a paucity of data both in conventional and hypofractionated regimens, particularly in the era of modern surgical and radiation techniques. We also found late toxicities can occur with increasing severity for many years after salvage radiotherapy. This analysis suggests that margin positivity and volume of surgical clips might identify patients at higher risk for late grade ≥3 toxicities, although the etiologies of these toxicities, whether surgery or radiation-related, are uncertain.

Improved survival with dose-escalated radiotherapy in stage III non-small-cell lung cancer: analysis of the National Cancer Database

BACKGROUND

Concurrent chemoradiation is the standard of care in non-operable stage III non-small-cell lung cancer (NSCLC). Data have suggested a benefit of dose escalation; however, results from the randomized dose-escalation trial RTOG 0617 revealed a lower survival rate with high-dose radiation. To evaluate the impact of dose escalation on overall survival (OS) in stage III NSCLC treated with chemoradiotherapy outside the controlled setting of a randomized trial, we carried out an observational, population-based investigation of the National Cancer Database (NCDB).

PATIENTS AND METHODS

A total of 33 566 patients with stage III NSCLC treated with chemoradiation from 2004 to 2012 and radiation doses between 59.4 and 85 Gy were included. The primary end point was OS, with median survival calculated via Kaplan-Meier. Univariate, multivariable and propensity-score matching analyses were carried out.

RESULTS

Patients were stratified by dose with median OS of: 18.8, 19.8 and 21.6 months for cohorts receiving 59.4-60, 61-69 and ≥70 Gy, respectively (P < 0.001). Granular dose analyses were carried out demonstrating increased OS with increasing radiation dose: median survival of 18.8, 21.1, 22.0 and 21.0 months for 59.4-60, 66, 70 and ≥71 Gy, respectively. While 66, 70 and ≥71 Gy resulted in increased OS in comparison with 59.4-60 Gy, no significant difference in OS was observed when comparing 66 with ≥71 Gy (P = 0.38).

CONCLUSIONS

Dose escalation above 60 Gy was associated with improved OS in this cohort of stage III NSCLC patients treated with chemoradiotherapy. A plateau of benefit was observed, with no additional improvement in OS with increased dose (≥71 Gy) compared with 66-70 Gy. With evidence suggesting worse OS and quality of life with increased dose, these data support investigation of the role of intermediate-dose radiation, and in the absence of randomized evidence, may be leveraged to justify utilization of intermediate-dose radiation.