Time Course of Radiological Lung Density Changes After Postmastectomy Radiotherapy

Abstract

The purpose of this study was to quantify the time course of radiological lung changes in patients after postmastectomy radiotherapy assessed from routine follow-up chest x-rays. Radiological density changes in the apex of the irradiated lung were quantified by a recent lung densitometry assay. Lung changes were expressed as the so-called Relative change in Equivalent Absorber Thickness (REAT). The clinical series comprised 329 patients treated with postmastectomy radiotherapy between 1978 and 1982. Of these patients 100 were treated with chemotherapy (CTX or CMF) and 41 were given tamoxifen as an additional adjuvant treatment; 290 patients (88.2%) had pretreatment x-rays and at least one x-ray after completion of radiotherapy and these were included in the study. A total of 2,209 chest x-rays was taken during follow-up, and among these 1921 x-rays (86.9%) were judged to be assessable. Late changes were defined as changes occurring more than a year after radiotherapy. A total of 280 patients had at least one chest x-ray taken more than one year after radiotherapy and these were evaluable with respect to late changes. There were 1,390 follow-up x-rays in these patients and 207 patients (73.9%) had three or more follow-up x-rays. Linear regression of REAT vs. observation time was used to identify three patterns of time changes: progressive, regressive, and stable. The results were as follows. Two phases of lung changes were observed. The early phase peaks around 6 months and the density changes may subsequently resolve, completely or in part. In most cases (173 patients or 84%), the lung density changes reached a stable level 12 months after irradiation. Yet, in 16 patients (7.7%) the lung changes progressed for five or more years. Regression of the density changes was seen in 18 patients (8.7%), and in some cases there were signs that this apparent regression was caused by contraction of the fibrotic tissue. We conclude that two phases of lung response can be distinguished and can be graded according to severity using this assay. Early lung changes reach a maximum around 6 months after RT. Late reactions reach a plateau in most patients after one year, but progress in some cases for five or more years.

Correlation Between Lung Density Changes Under Different Dose Gradients and Radiation Pneumonitis—Based on an Analysis of Computed Tomography Scans During Esophageal Cancer Radiotherapy

“…Unfortunately, it was not successful. These results are different from previous studies (6,7,23,24) on the dose-density relationship of lung after RT. They have established a dosedensity curve and found that with the increase of radiation dose, lung density increases, and this lung density dose-dependent increase has a time-dependent characteristic.…”

“…As mentioned above, early studies have confirmed that changes in lung density obtained by quantitative analysis do not necessarily represent the inevitability of RP, and this density change changes with time after RT (7,8,24). Although lung CT imaging is an effective diagnostic tool for RP, it cannot predict the occurrence time of RP in the early stage, which is a difficult problem in clinical practice.…”

“…Due to the limited number of cases, the correlation analysis between D Hu and RP at a certain time point cannot be realized. In addition, we have found from some studies (7,24) that D Hu after RT is time-correlated with the occurrence of RP, so it seems meaningless to use a single time point to predict the occurrence of RP. It is a little difficult to realize the clinical practice value of this study in this respect, but this research idea is feasible.…”

Analysis of Single Nucleotide Polymorphisms and Radiation Sensitivity of the Lung Assessed With an Objective Radiologic Endpoin

“…Radiographic abnormalities, indicative of injury, are noted in the lung almost immediately after thoracic RT. 27,37 The radiographic findings most extensively studied are increased density on CT and decreased pulmonary perfusion on SPECT. Radiation dose is the single most important contributor to the development of radiographic abnormalities.…”

Single nucleotide polymorphisms and unacceptable late toxicity in breast cancer adjuvant radiotherapy: a case report

“…Tissue hypoxia, drugs employed, and genetic features may also affect the clinical tissue radiosensitivity after a normal fractionated schedule. Drugs such as chemotherapy or hormone therapy have been demonstrated to enhance subcutaneous fibrosis after radiotherapy as reported by Skoczylas et al and Bentzen et al who analyzed the impact of adjuvant cyclophosphamide, methotrexate, and fluorouracil (CMF) or tamoxifen on cosmesis 3,4. On the other hand, the use of aromatase inhibitors seems to exert a protective effect on post-radiation-induced lung fibrosis 5.…”