The role of bone marrow and spleen irradiation in the development of acute hematologic toxicity during chemoradiation for esophageal cancer

Purpose

The purpose of this study was to determine the impact of splenic and thoracic bone marrow irradiation on hematologic toxicity in the setting of chemoradiation therapy for esophageal cancer.

Methods and materials

We analyzed 60 patients with carcinoma of the distal esophagus or gastroesophageal junction who received concurrent chemoradiation in the preoperative or definitive setting. Dosimetric and volumetric parameters were calculated for the spleen, thoracic spine, and posterior ribs. The primary endpoint was grade ≥3 hematologic toxicity (HT3+). Associations were assessed using logistic and linear regression models.

Results

Twenty-one patients (35%) experienced HT3+, including 18 patients with leukopenia and 5 with thrombocytopenia. Higher spleen V5-V20 was correlated with a lower risk of HT3+ on multivariable analysis (odds ratio: 0.83 per 10 cm³ increase in V10; P = .013). A dose-dependent decrease in spleen volume was observed after radiation therapy, and a greater decrease was independently associated with a lower risk of HT3+ (odds ratio: 0.93 per 1% volume decrease; P = .014). Dosimetric parameters of the thoracic spine were not significantly associated with HT3+.

Conclusions

A greater decrease in spleen size after radiation therapy and a higher spleen V5-V20 were independently associated with a lower risk of severe hematologic toxicity. Splenic irradiation may mitigate leukopenia associated with chemoradiation therapy.

The Impact of Splenectomy in Myelofibrosis Patients before Allogeneic Hematopoietic Stem Cell Transplantation

Performing a pretransplantation splenectomy in patients with myelofibrosis (MF) is a matter of debate, as while the procedure improves hematological recovery, it may lead to severe morbidities. We retrospectively analyzed data from 85 consecutive patients who underwent transplantation in our center for MF, including 39 patients who underwent splenectomy before their transplantation. A majority of them had primary MF (78%), were considered high-risk patients (84% dynamic international prognostic scoring system intermediate-2 or higher), and had received transplants from HLA-matched sibling donors (56%) after a reduced-intensity conditioning regimen (82%). One-half of all splenectomized patients presented surgical or postsurgical morbidities, most frequently thrombosis and hemorrhage. After adjustment using Cox models, pretransplantation splenectomy was not associated with nonrelapse mortality or post-transplantation relapse but with an improved overall survival (OS) and event-free survival (EFS). We conclude that some patients with huge splenomegaly may undergo pretransplantation splenectomy without a deleterious impact on post-transplantation outcomes. OS and EFS improvement should in confirmed in controlled study.

Splenic irradiation for splenomegaly: A systematic review

Splenic irradiation (SI) is a palliative treatment option for symptomatic splenomegaly (i.e. for pain, early satiety, pancytopenia from sequestration) secondary to hematologic malignancies and disorders. The purpose of the current article is to review the literature on SI for hematologic malignancies and disorders, including: (1) patient selection and optimal technique; (2) efficacy of SI; and (3) toxicities of SI. PICOS/PRISMA methods are used to select 27 articles including 766 courses of SI for 486 patients from 1960 to 2016. The most common cancers treated included chronic lymphocytic leukemia and myeloproliferative disorders; the most common regimen was 10Gy in 1Gy fractions over two weeks, and 27% of patients received retreatment. A partial or complete response (for symptoms, lab abnormalities) was obtained in 85-90% of treated patients, and 30% were retreated within 6-12months. There was no correlation between biologically equivalent dose of radiation therapy and response duration, pain relief, spleen reduction, or cytopenia improvement (r2 all <0.4); therefore, lower doses (e.g. 5Gy in 5 fractions) may be as effective as higher doses. Grade 3-4 toxicity (typically leukopenia, infection) was noted in 22% of courses, with grade 5 toxicity in 0.7% of courses. All grade 5 toxicities were due to either thrombocytopenia with hemorrhage or leukopenia with sepsis (or a combination of both); they were sequelae of cancer and not directly caused by SI. In summary, SI is generally a safe and efficacious method for treating patients with symptomatic splenomegaly.

Radiation exposure of the spleen during (177)Lu-DOTATATE treatment and its correlation with haematological toxicity and spleen volume

Background

Somatostatin analogue-based radionuclide therapy with ¹⁷⁷Lu-DOTATATE is an important treatment option for patients with advanced neuroendocrine tumours overexpressing somatostatin receptors. In addition to the kidneys, the bone marrow is a major dose-limiting organ. The correlation between developed haematological toxicity and absorbed dose to the bone marrow is poor, which indicates that other factors affect haematological response. The spleen has an important role in the haematopoetic system, including being a reservoir for blood cells. It is also the organ that receives the highest mean absorbed dose during ¹⁷⁷Lu-DOTATATE treatment. The aim of this study was to analyse mean absorbed dose to the spleen and its correlation with haematological toxicity, and to explore changes in splenic volume.

The study included 41 patients treated with 7.2 GBq (3.5–8.3 GBq) of ¹⁷⁷Lu-DOTATATE on two to five occasions. Following each fraction, planar whole-body scans were acquired at 2, 24, 48, and 168 h, and a SPECT/CT at 24 h post-injection. Mean absorbed spleen dose was calculated utilising planar images for time-activity data and SPECT to adjust activity amounts. Splenic volume information was collected from diagnostic CT scans at baseline and follow-up.

Results

Median and total absorbed spleen doses were estimated to 4.5 and 15 Gy, respectively. Total absorbed spleen dose correlated with decrease in Hb (p = 0.02), but not WBC (p = 0.31) or PLT (p = 0.65) counts. For patients without bone metastases, mean absorbed spleen dose correlated with decrease in PLT (p = 0.04) but not Hb (p = 0.16) or WBC (p = 0.42) counts. The spleen volume was reduced to 75 % (p < 0.001) of original values (200 vs. 260 ml) at a mean follow-up of 36 months.

Conclusions

Haematological toxicity according to Hb counts was moderately but significantly correlated with total absorbed spleen dose. This supports the possibility that radiation exposure of the spleen affects overall haematological response during ¹⁷⁷Lu-DOTATATE treatment.