[Reirradiation of normal tissues: preclinical radiobiological data]

[Repair and time-dose factor: The example of spinal cord irradiation]

The question whether a reirradiation is possible, with either curative of palliative intent, is a frequent issue and a true therapeutic challenge, in particular for a critical organ sensitive to cumulative dose, such as the spinal cord. Preclinical experimental data, based on debatable models that are hardly transferable to patients, suggest that there is a possibility of reirradiation, beyond the classical threshold for dose constraints, taking into account the "time-dose factor". Although the underlying biological mechanisms are however uncertain, scarce clinical data seem to confirm that the tolerance of spinal cord to reirradiation does exist, provided that a particular attention to total dose is given. In the context where modern stereotactic irradiation facilities expand therapeutic perspectives, we review the literature on possibilities of reirradiation, through the example of spinal cord reirradiation.

[A case of cutaneous mammary re-irradiation]

In early-stage breast cancer, radiotherapy delivered after conservative surgery leads to a reduction in the risk of local recurrences by approximately two thirds. However, some local recurrences can occur in a previously irradiated region and be relevant for a second radiotherapy, exposing to an increased risk of adverse effects. We describe here the observation of a 66-year-old woman treated for a triple negative ductal infiltrative carcinoma of the left breast, who presented an early locoregional recurrence, notably as skin nodules, developed within the irradiated volume and progressing on chemotherapy. The patient was treated by re-irradiation performed concomitantly to oral chemotherapy by capecitabine.

Mast cells and ionizing radiation induce a synergistic expression of inflammatory genes in endothelial cells by a mechanism involving p38α MAP kinase and (p65) NF-κB activation

Vascular endothelium is a key compartment involved in the development of normal tissue toxicity associated with cancer radiation therapy, i.e., acute inflammation and late fibrosis. Radiation-induced endothelial cell activation has been extensively studied, and activated endothelial cells are characterized by increased expression of inflammatory mediators and adhesion molecules, and activation of the coagulation and thrombosis pathways. However, little is known about the role of vascular endothelium interaction with resident immune cells, such as mast cells on its response to irradiation. Here, we report that endothelial exposure to mast cell conditioned medium and irradiation induces a synergistic expression of many inflammatory genes including interleukin-6 and interleukin-8, CXCL2 and E-selectin. This synergy is blocked by the histamine H1 receptor antagonist mepyramine and partially mimicked by exogenous histamine addition before irradiation. Using pharmacological and molecular inhibition approaches, we show the p38α MAP kinase and p65 (NF-κB) dependence of the synergy. Moreover, our data show a link between both pathways, with p65 (NF-κB) being downstream of p38. These data highlight the possible exacerbation of the radiation-induced endothelial inflammatory response by its interactions with immune cells. It also suggest that p38α MAP kinase and p65 (NF-κB) inhibition in vascular endothelium may limit excessive tissue inflammation induced by radiation therapy, and thereby limit the associated acute and late tissue damage.

[Breast conserving surgery in locoregional treatment of breast carcinoma after Hodgkin lymphoma]

PURPOSE

To report characteristics and outcome of breast cancer after irradiation for Hodgkin lymphoma with special focus on breast conservation surgery.

PATIENTS AND METHODS

Medical records of 72 women who developed either ductal carcinoma in situ or stage I-III invasive carcinoma of the breast after Hodgkin lymphoma between 1978 and 2009 were retrospectively reviewed.

RESULTS

Median age at Hodgkin lymphoma diagnosis was 23 years old. Median total dose received by the mediastinum was 40 Gy, mostly by a mantle field technique. Breast cancer occurred after a median time interval of 21 years. Ductal invasive carcinoma and ductal carcinoma in situ represented respectively 71% and 19% of the cases. Locoregional treatment for breast cancer consisted of mastectomy with or without radiotherapy in 39 patients and of lumpectomy with or without adjuvant radiotherapy in 32 patients. The isocentric lateral decubitus radiation technique was used in 17 patients after breast conserving surgery (57%). With a median follow-up of 7 years, 5-year overall survival rate and locoregional control rate were respectively 74.5% and 82% for invasive carcinoma and 100% and 92% for in situ carcinoma. Thirteen patients died of progressive breast cancer and contralateral breast cancer was diagnosed in ten patients (14%).

CONCLUSIONS

Breast conserving treatment can be an option for breast cancers that occur after Hodgkin lymphoma despite prior thoracic irradiation. It should consist of lumpectomy and adjuvant breast radiotherapy with use of adequate techniques, such as the lateral decubitus isocentric position.

Effect of total body irradiation on late lung effects: hidden dangers

PURPOSE

In our ongoing investigation into the consequences of a radiological terrorism or nuclear dispersion event, we assessed whether a dose range that is believed to be sub-threshold for the development of lung endpoints results in late pathological changes and, secondarily, whether those late changes affect the lung's ability to respond to subsequent challenge.

MATERIALS AND METHODS

C57BL/6J mice received total body irradiation (0.5-10 Gy) and were followed for 6-18 months after irradiation. At 12 and 15 months, a subset of mice was exposed to a second challenge (aerosolised lipopolysaccharide [LPS]).

RESULTS

Cytokines shown to be upregulated early (hours) following irradiation (interleukin [IL]6, keratinocyte chemoattractant [KC], IL1B, and IL1R2) demonstrated increases in messenger ribose nucleic acid (mRNA) expression at late time points, beginning at nine months. Although persistent, dose-dependent increases in T cell counts were seen, no other overt changes in pathophysiology were observed. Nonetheless, animals that were exposed to a secondary challenge at late time points demonstrated an increased inflammatory cell recruitment and persistence in response relative to controls.

CONCLUSIONS

We propose that, following doses that elicit little change in pathophysiology, sub-clinical radiation-induced injury increases the lungs' susceptibility to a secondary challenge, possibly through a radiation-induced alteration in the immune defense system.