In vivo measurement of dose distribution in patients' lymphocytes: helical tomotherapy versus step-and-shoot IMRT in prostate cancer

The paradox of radiation and T cells in tumors

In this review we consider what appears to be a paradox in immunotherapies based around radiation therapy. The paradox is based on three main points. 1. That T cells are needed for radiation's efficacy; 2. That tumor-specific T cells are enriched in the field of treatment; and 3. That radiation kills T cells in the treatment field. We discuss evidence of the effect of radiation on T cells in the field given their ongoing movement in and out of tissues and the tumor, and how the movement of T cells impacts the treated primary tumor and untreated distant metastases. Given this evidence, we revisit the paradox to understand how the extraordinary efficacy of radiation and immunity in preclinical models is dependent on this radiation sensitive cell.

Radiation-induced DNA double-strand breaks in peripheral leukocytes and therapeutic response of heel spur patients treated by orthovoltage X-rays or a linear accelerator

Purpose

Biodosimetric assessment and comparison of radiation-induced deoxyribonucleic acid (DNA) double-strand breaks (DSBs) by γH2AX immunostaining in peripheral leukocytes of patients with painful heel spur after radiation therapy (RT) with orthovoltage X‑rays or a 6-MV linear accelerator (linac). The treatment response for each RT technique was monitored as a secondary endpoint.

Patients and methods

22 patients were treated either with 140-kV orthovoltage X‑rays (n = 11) or a 6-MV linac (n = 11) with two weekly fractions of 0.5 Gy for 3 weeks. In both scenarios, the dose was prescribed to the International Commission on Radiation Units and Measurements (ICRU) dose reference point. Blood samples were obtained before and 30 min after the first RT session. γH2AX foci were quantified by immunofluorescence microscopy to assess the yield of DSBs at the basal level and after radiation exposure ex vivo or in vivo. The treatment response was assessed before and 3 months after RT using a five-level functional calcaneodynia score.

Results

RT for painful heel spurs induced a very mild but significant increase of γH2AX foci in patients’ leukocytes. No difference between the RT techniques was observed. High and comparable therapeutic responses were documented for both treatment modalities. This trial was terminated preliminarily after an interim analysis (22 patients randomized).

Conclusion

Low-dose RT for painful heel spurs with orthovoltage X‑rays or a 6-MV linac is an effective treatment option associated with a very low and comparable radiation burden to the patient, as confirmed by biodosimetric measurements.

[Normal tissue: radiosensitivity, toxicity, consequences for planning]

Along with chemotherapy, surgery and immunotherapy, radiotherapy is a mainstay of cancer treatment. Considering the improving survival rates for various malignancies during the past decades, the importance of radiation-induced late normal tissue response is increasing. Quality of life is becoming an important issue in modern cancer treatment and is correlated with acute and late normal tissue response after radiotherapy. A profound understanding of radiation-induced normal tissue response is necessary to sufficiently diagnose and treat radiation-induced side effects and thereby increase the patients' quality of life. Here, the various normal tissue responses in consideration of the radiation biology are specified and prospective options to attenuate radiation-induced side effects are discussed.

Prostate cancer treated with brachytherapy; an exploratory study of dose-dependent biomarkers and quality of life

BACKGROUND

Low-dose-rate permanent prostate brachytherapy (PPB) is an attractive treatment option for patients with localised prostate cancer with excellent outcomes. As standard CT-based post-implant dosimetry often correlates poorly with late treatment-related toxicity, this exploratory (proof of concept) study was conducted to investigate correlations between radiation - induced DNA damage biomarker levels, and acute and late bowel, urinary, and sexual toxicity.

METHODS

Twelve patients treated with ¹²⁵I PPB monotherapy (145Gy) for prostate cancer were included in this prospective study. Post-implant CT based dosimetry assessed the minimum dose encompassing 90% (D_90%) of the whole prostate volume (global), sub-regions of the prostate (12 sectors) and the near maximum doses (D_0.1cc, D_2cc) for the rectum and bladder. Six blood samples were collected from each patient; pre-treatment, 1 h (h), 4 h, 24 h post-implant, at 4 weeks (w) and at 3 months (m). DNA double strand breaks were investigated by staining the blood samples with immunofluorescence antibodies to γH2AX and 53BP1 proteins (γH2AX/53BP1). Patient self-scored quality of life from the Expanded Prostate Cancer Index Composite (EPIC) were obtained at baseline, 1 m, 3 m, 6 m, 9 m, 1 year (y), 2y and 3y post-treatment. Spearman's correlation coefficients were used to evaluate correlations between temporal changes in γH2AX/53BP1, dose and toxicity.

RESULTS

The minimum follow up was 2 years. Population mean prostate D_90% was 144.6 ± 12.1 Gy and rectal near maximum dose D_0.1cc = 153.0 ± 30.8 Gy and D_2cc = 62.7 ± 12.1 Gy and for the bladder D_0.1cc = 123.1 ± 27.0 Gy and D_2cc = 70.9 ± 11.9 Gy. Changes in EPIC scores from baseline showed high positive correlation between acute toxicity and late toxicity for both urinary and bowel symptoms. Increased production of γH2AX/53BP1 at 24 h relative to baseline positively correlated with late bowel symptoms. Overall, no correlations were observed between dose metrics (prostate global or sector doses) and γH2AX/53BP1 foci counts.

CONCLUSIONS

Our results show that a prompt increase in γH2AX/53BP1foci at 24 h post-implant relative to baseline may be a useful measure to assess elevated risk of late RT - related toxicities for PPB patients. A subsequent investigation recruiting a larger cohort of patients is warranted to verify our findings.

Partial-Body Irradiation in Patients with Prostate Cancer Treated with IMRT Has Little Effect on the Composition of Serum Proteome

Partial body irradiation during cancer radiotherapy (RT) induces a response of irradiated tissues that could be observed at the level of serum proteome. Here we aimed to characterize the response to RT in group of patients treated because of prostate cancer. Five consecutive blood samples were collected before, during, and after the end of RT in a group of 126 patients who received definitive treatment with a maximum dose of 76 Gy. Serum peptidome, which was profiled in the 2000–16,000 Da range using MALDI-MS. Serum proteins were identified and quantified using the shotgun LC-MS/MS approach. The majority of changes in serum peptidome were detected between pre-treatment samples and samples collected after 3–4 weeks of RT (~25% of registered peptides changed their abundances significantly), yet the intensity of observed changes was not correlated significantly with the degree of acute radiation toxicity or the volume of irradiated tissues. Furthermore, there were a few serum proteins identified, the abundances of which were different in pre-RT and post-RT samples, including immunity and inflammation-related factors. Observed effects were apparently weaker than in comparable groups of head and neck cancer patients in spite of similar radiation doses and volumes of irradiated tissues in both groups. We concluded that changes observed at the level of serum proteome were low for this cohort of prostate cancer patients, although the specific components involved are associated with immunity and inflammation, and reflect the characteristic acute response of the human body to radiation.