Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2008 Oct 1;72(2):568-74.
doi: 10.1016/j.ijrobp.2008.04.053.

Analysis of radiation pneumonitis risk using a generalized Lyman model

Susan L Tucker  1 , H Helen Liu, Zhongxing Liao, Xiong Wei, Shulian Wang, Hekun Jin, Ritsuko Komaki, Mary K Martel, Radhe Mohan
Affiliations

Analysis of radiation pneumonitis risk using a generalized Lyman model

Susan L Tucker et al. Int J Radiat Oncol Biol Phys. .

Erratum in

  • Int J Radiat Oncol Biol Phys. 2010 Sep 1;78(1):316-7. Dosage error in article text

Abstract

Purpose: To introduce a version of the Lyman normal-tissue complication probability (NTCP) model adapted to incorporate censored time-to-toxicity data and clinical risk factors and to apply the generalized model to analysis of radiation pneumonitis (RP) risk.

Methods and materials: Medical records and radiation treatment plans were reviewed retrospectively for 576 patients with non-small cell lung cancer treated with radiotherapy. The time to severe (Grade >/=3) RP was computed, with event times censored at last follow-up for patients not experiencing this endpoint. The censored time-to-toxicity data were analyzed using the standard and generalized Lyman models with patient smoking status taken into account.

Results: The generalized Lyman model with patient smoking status taken into account produced NTCP estimates up to 27 percentage points different from the model based on dose-volume factors alone. The generalized model also predicted that 8% of the expected cases of severe RP were unobserved because of censoring. The estimated volume parameter for lung was not significantly different from n = 1, corresponding to mean lung dose.

Conclusions: NTCP models historically have been based solely on dose-volume effects and binary (yes/no) toxicity data. Our results demonstrate that inclusion of nondosimetric risk factors and censored time-to-event data can markedly affect outcome predictions made using NTCP models.

PubMed Disclaimer

Figures

Figure 1
Figure 1
Overall survival and freedom from grade ≥ 3 RP and during the first 12 months after start of radiotherapy.
Figure 2
Figure 2
Histogram showing the distribution of times to grade ≥ 3 RP, adjusted to take into account the number of patients alive and at risk of RP at each time point. The dashed curve represents a log-normal density function with parameters μ = 1.31 and σ = 0.42 (equation 5).
Figure 3
Figure 3
NTCP values computed from the fit of the generalized Lyman model as a function of mean lung dose (model parameters from column 2 of Table 1). Points show Kaplan-Meier estimates of RP incidence at 1 year in patient subgroups. The cohorts of smokers and former smokers were divided into 4 groups each according to mean lung dose: MLD < 15 Gy, 15-20 Gy, 20-25 Gy, and > 25 Gy, The cohort of nonsmoking patients was divided into two subgroups with MLD < 20 Gy and MLD > 20 Gy, Points are plotted at the average MLD value for each subgroup. Horizontal error bars indicate + 1 standard deviation in MLD; vertical error bars indicate + 1 standard error in the estimated RP incidence.
Figure 4
Figure 4
Freedom from grade ≥ 3 RP among patient subgroups defined by NTCP value from the fit of the generalized Lyman model with n = 1 (Table 1, column 2).
See this image and copyright information in PMC

References

    1. Lyman JT. Complication probability as assessed from dose-volume histograms. Radiat Res Suppl. 1985;8:S13–19. - PubMed
    1. Hernando ML, Marks LB, Bentel GC, et al. Radiation-induced pulmonary toxicity: a dose-volume histogram analysis in 201 patients with lung cancer. Int J Radiat Oncol Biol Phys. 2001;51:650–659. - PubMed
    1. Kahan Z, Csenki M, Varga Z, et al. The risk of early and late lung sequelae after conformal radiotherapy in breast cancer patients. Int J Radiat Oncol Biol Phys. 2007;68:673–681. - PubMed
    1. Johansson S, Bjermer L, Franzen L, et al. Effects of ongoing smoking on the development of radiation-induced pneumonitis in breast cancer and oesophagus cancer patients. Radiother Oncol. 1998;49:41–47. - PubMed
    1. Jin HKLH, Tucker SL, Liu HH, Wei X, Yom SS, Wang SL, Komaki R, Chen Y, Martel MK, Mohan R, Cox JD, Liao Z. Dose-volume thresholds for the risk of treatment-related pneumonitis in inoperable non-small cell lung cancer treated with definitive radiotherapy. submitted. - PMC - PubMed

Publication types