Effects of hyperbaric oxygen exposure on experimental head and neck tumor growth, oxygenation, and vasculature

Does hyperbaric oxygen therapy play a role in the management of osteoradionecrosis? A survey of Dutch oral and maxillofacial surgeons

For decades, hyperbaric oxygen (HBO) has often been part of the treatment of osteoradionecrosis (ORN), despite controversy in the literature about its efficacy. An online survey was conducted to investigate the use of HBO in the treatment of ORN by Dutch oral and maxillofacial surgeons and to assess their perception of its efficacy. Of the 53 Dutch oral and maxillofacial surgery units contacted, 49 (92%) replied. Thirty-five were not head and neck cancer (HNC) units or preferred partner (PP-HNC) units recognized by the Dutch Head and Neck Association. All HNC and PP-HNC units (group 1) treated ORN patients, compared to only 12 (34%) of the non-HNC units (group 2). The average number of ORN patients seen and treated was higher in group 1. The units in group 1 more often referred patients for HBO therapy (HBOT) than those in group 2 (93% vs 84%). The efficacy of HBOT in curing ORN, rated on a scale of 1 to 5 points, was 3.7 in group 1 and 3.2 in group 2. This survey shows a trend towards centralization of ORN care to more experienced units. These units tend to use HBOT in curing ORN.

Pharyngocutaneous fistula following total laryngectomy: analysis of risk factors, prognosis and treatment modalities

The aim of this study was to establish the incidence, risk factors, and the management of pharyngocutaneous fistula (PCF) after primary and salvage total laryngectomy. A retrospective, match-paired analysis of 86 patients who developed fistula after total laryngectomy was carried out and compared with a control group of 86 patients without fistula, randomly selected from a pool of 352 total laryngectomies, performed between January 1999 to October 2014. The overall incidence of PCF in the series was 24.4%; we recorded rates of 19.0%, 28.6% and 30.3% following primary total laryngectomy (PTL), salvage laryngectomy post-radiotherapy (RT-STL) and salvage laryngectomy postchemoradiotherapy (CRT-STL), respectively. Multivariate analysis revealed that the relative risk of fistula was respectively 2.47, 3.09 and 7.69 for hypoalbuminaemia ≤3.5 g/dL, RT-STL and CRT-STL. An early onset of PCF within 10 postoperative days was recorded in case of salvage total laryngectomy. The management of PCF significantly differed between PTL, RT-STL and CTRT-STL, with exclusive conservative treatment for PTL (93.55%), while in the CRT-STL group surgical closure with regional flaps (58.82%) prevailed. Conservative management, adjuvant hyperbaric oxygen therapy and surgical closure were equally distributed in the RT-STL group. Thorough knowledge of patient-related risk factors and its prognostic value, allows the surgeon to better evaluate preventive strategies with the aim of minimising fistula formation, hospitalisation times and related costs.

Salvage Transoral Videolaryngoscopic Surgery for radiorecurrent hypopharyngeal and supraglottic cancer

OBJECTIVE

To evaluate the feasibility of Transoral Videolaryngoscopic Surgery (TOVS) for radiorecurrent supraglottic and hypopharyngeal cancer, and to compare survival and complications between primary and radiorecurrent cases.

METHODS

Twelve cases of salvage TOVS for radiorecurrent cancer and 53 cases of TOVS as an initial treatment (primary cases) were evaluated. Days to resume soft diet, Functional Outcomes of Swallowing Scale (FOSS), postoperative complications, epithelization days and survival outcomes were assessed by retrospective chart review.

RESULTS

FOSS score was significantly worse in salvage cases compared with primary cases. Bleeding and airway compromise was slightly greater in salvage cases than in primary cases; however, this was not statistically significant. Wound healing was significantly delayed in salvage cases compared with primary cases (P<0.001). In primary cases, wounds were re-epithelized within 60 days in 83% of patients and within 90 days in almost all patients, while in salvage cases 42% of patients required more than 90 days for wound healing. In salvage cases, the 5-year overall survival, disease specific survival rate, local control rate, and laryngeal preservation rate was 85.7%, 85.7%, 62.5%, and 78.0%, respectively, and 85.7%, 98.0%, 91.3%, and 97.8%, respectively, for primary cases. Local control rate was significantly better in primary cases than in salvage cases.

CONCLUSION

Salvage TOVS was feasible in highly selected cases. After serial transoral surgery, the final laryngeal preservation rate was satisfactory. Swallowing function in salvage cases tended to be worse than in primary cases, and a significantly longer time was required for wound healing.

Hyperbaric oxygen as an adjunctive therapy in treatment of malignancies, including brain tumours

Hyperbaric oxygen (HBO) therapy is widely used as an adjunctive treatment for various pathological states, predominantly related to hypoxic and/or ischaemic conditions. It also holds promise as an approach to overcoming the problem of oxygen deficiency in the poorly oxygenated regions of the neoplastic tissue. Occurrence of local hypoxia within the central areas of solid tumours is one of the major issues contributing to ineffective medical treatment. However, in anti-cancer therapy, HBO alone gives a limited curative effect and is typically not applied by itself. More often, HBO is used as an adjuvant treatment along with other therapeutic modalities, such as radio- and chemotherapy. This review outlines the existing data regarding the medical use of HBO in cancer treatment, with a particular focus on the use of HBO in the treatment of brain tumours. We conclude that the administration of HBO can provide many clinical benefits in the treatment of tumours, including management of highly malignant gliomas. Applied immediately before irradiation, it is safe and well tolerated by patients, causing rare and limited side effects. The results obtained with a combination of HBO/radiotherapy protocol proved to be especially favourable compared to radiation treatment alone. HBO can also increase the cytostatic effect of certain drugs, which may render standard chemotherapy more effective. The currently available data support the legitimacy of conducting further research on the use of HBO in the treatment of malignancies.

Optical Imaging of Tumor Response to Hyperbaric Oxygen Treatment and Irradiation in an Orthotopic Mouse Model of Head and Neck Squamous Cell Carcinoma

Purpose

Hyperbaric oxygen therapy (HBOT) is used in the treatment of radiation-induced tissue injury but its effect on (residual) tumor tissue is indistinct and therefore investigated in this study.

Procedures

Orthotopic FaDu tumors were established in mice, and the response of the (irradiated) tumors to HBOT was monitored by bioluminescence imaging. Near infrared fluorescence imaging using AngioSense750 and Hypoxisense680 was applied to detect tumor vascular permeability and hypoxia.

Results

HBOT treatment resulted in accelerated growth of non-irradiated tumors, but mouse survival was improved. Tumor vascular leakiness and hypoxia were enhanced after HBOT, whereas histological characteristics, epithelial-to-mesenchymal transition markers, and metastatic incidence were not influenced.

Conclusions

Squamous cell carcinoma responds to HBOT with respect to tumor growth, vascular permeability, and hypoxia, which may have implications for its use in cancer patients. The ability to longitudinally analyze tumor characteristics highlights the versatility and potential of optical imaging methods in oncological research.

Electronic supplementary material

The online version of this article (doi:10.1007/s11307-015-0834-8) contains supplementary material, which is available to authorized users.

Spatial oxygenation profiles in tumors during normo- and hyperbaric hyperoxia

BACKGROUND

Inspiratory hyperoxia reduces tumor hypoxia, which is responsible for limited radiosensitivity of tumors. However, very little is known about the heterogeneity of intratumoral oxygenation during this supportive treatment. The study analyzes whether local hypoxia is still present during normobaric and hyperbaric inspiratory hyperoxia and whether the addition of CO2 to the inspiratory gas affects the spatial pO2 distribution.

MATERIAL AND METHODS

Tumor oxygenation of experimental DS-sarcomas in rats was assessed by polarographic needle electrodes at 1 and 2 atm (bar) environmental pressure during pure O2 or carbogen (95 % O2 + 5 % CO2) breathing. Up to 320 individual pO2 measurements were performed in a strictly oriented grid resulting in an oxygenation profile in a horizontal tumor layer.

RESULTS

In the experimental tumors used the oxygenation showed pronounced heterogeneities with closely adjacent hypoxic and oxygenated regions. This heterogeneity was still visible under normobaric hyperoxia where large confluent hypoxic regions were detectable. At 1 atm, the addition of CO2 improved tumor oxygenation significantly (at least in large tumors). At 2 atm, only very small local regions of hypoxia were detected. However, under this condition hypercapnia had no impact on tumor oxygenation.

CONCLUSIONS

The data show that even under hyperbaric hyperoxia, hypoxic regions are detectable despite the average pO2 increased by a factor of 100. The results also clearly indicate that the oxygenation pattern improves disproportionally with increasing environmental pressure.

HBO: a possible supplementary therapy for oral potentially malignant disorders

Oral potentially malignant disorders (OPMDs) are chronic inflammatory diseases in which cells suffer hypoxia referring to deprivation of adequate oxygen supply. Hyperbaric oxygen treatment (HBO), which can increase oxygen tension and delivery to oxygen-deficient tissue, is a supplementary therapy to improve or cure disorders involving hypoxia. Although the applications of HBO in wound healings, acute ischemic stroke, radiation-induced soft tissue injury and cancers are extensively reported, there are only few studies on their effect in OPMDs. Not only does HBO furnish oxygen-it also possesses potent anti-inflammatory properties. At the cellular level, HBO can decrease lymphocyte proliferation and promote apoptosis of fibroblasts. At the molecular level, it can decrease expression of HIF, ICAM-1, TNF-α, TGF-β, and IFN-γ, as well as increase vascular VEGF expression and angiogenesis. Thus, we hypothesize that HBO may contribute to treat OPMDs, including oral lichen planus, oral leukoplakia, and oral submucous fibrosis both at the cellular level and the molecular level, and that it would be a safe and inexpensive therapeutic strategy.

Oral surgery in patients undergoing chemoradiation therapy

Oral health care in patients undergoing chemotherapy and/or radiation therapy can be complex. Care delivered by a multidisciplinary approach is timely and streamlines the allocation of resources to provide prompt care and to attain favorable outcomes. A hospital dentist, oral and maxillofacial surgeon, and a maxillofacial prosthodontist must be involved early to prevent avoidable oral complications. Prevention and thorough preparation are vital before the start of chemotherapy and radiation therapy. Oral complications must be addressed immediately and, even with the best management, can cause delays and interruption in treatment, with serious consequences for the outcome and prognosis.

Effect of hyperbaric oxygen therapy on a murine squamous cell carcinoma model

BACKGROUND

Hyperbaric oxygen (HBO) therapy is sometimes used to assist in wound healing after major head and neck cancer surgery. However, there is concern that HBO treatments might enhance the growth of any residual microscopic disease. This was studied in a mouse model of squamous cell carcinoma (SCC).

METHODS

SCC-VII/SF tumor cells were cultured, and then injected (3 × 10(3) cells) into C3H/HeJ mice in 5 groups: subcutaneous (SQ) control (n = 13), SQ-immediate (n = 12), SQ-delayed (n = 13), tail vein control (n = 8), and tail vein immediate (n = 9). The 3 experimental groups were subjected to HBO therapy, 2.4 atm for 90 minutes, 5 days per week for 4 weeks, starting on postinjection day 3 ("immediate") or 10 ("delayed"). Tumors in the SQ mice were measured 3 times per week. Lung metastases in the tail vein mice were counted at necropsy.

RESULTS

At postimplantation day 28, when the immediate group completed its HBO therapy, the tumor volume in the SQ-immediate group was 49.1% higher than the control group, and the SQ-delayed group was 105.1% higher than controls (p < .05). Two weeks later, the SQ-immediate group and SQ-delayed group tumor volumes were still significantly higher than controls, but the difference was smaller (18.4% and 43.8%, respectively; p < .05 only for the delayed group). The tail vein groups had similar numbers of lung metastases, with a mean of 8.7 metastases in the control group and 9.0 metastases in the HBO group (not significant [NS]).

CONCLUSION

This study suggests that HBO therapy does accelerate the growth of microscopic foci of SCCs. This finding differs from some earlier studies and warrants further study.

In vivo hyperoxia induces hypoxia-inducible factor-1α overexpression in LNCaP tumors without affecting the tumor growth rate

Hypoxia is a recognized cause for solid tumors malignancy and resistance, probably via hypoxia-induced overexpression of the hypoxia-inducible factor (HIF)-1α, major modulator of the cell response to oxygen deprivation. Although hyperoxia, the opposite condition, may represent a key issue to assess this paradigm, its effect on tumor growth and HIF-1α expression remains unclear. To test whether hyperoxia and hypoxia have divergent effects, and to better focus into the role of HIF-1α in vivo, athymic mice xenografted with LNCaP cells were exposed for 28 days to atmospheres containing 10, 21 or 30% O2. Whereas the xenografts grew twice faster in hypoxia, their growth rates in hyperoxia and normoxia were similar. To analyze the involved molecular mechanisms, we performed various assays in xenograft tissues. Faster xenografts growth in hypoxia was associated with higher phosphorylation of protein kinase B (Akt) and higher expression of Ki67, both related with pro-survival and cell proliferation pathways. By contrast, the expression level of HIF-1α was similar in normoxia and hypoxia, but paradoxically twice higher in hyperoxia. The protein level of the nuclear factor (erythroid-derived 2)-like 2 (Nrf2) was also higher in hyperoxia, suggesting marked cell response to redox imbalance. Whereas both the vascular-endothelial growth factor (VEGF) and its receptor VEGF-R2 were overexpressed in hyperoxia, the tissue hemoglobin content was not increased, despite a slight reduction in vascularization. As a whole, this data indicates that the xenografts growth rate was independent of HIF-1α expression level, suggesting that in an in vivo setting alternative more effective proliferative paths associated with the cell response to the redox imbalance may override the paths linked to HIF-1α signaling.

Hyperbaric oxygen therapy and cancer--a review

Hypoxia is a critical hallmark of solid tumors and involves enhanced cell survival, angiogenesis, glycolytic metabolism, and metastasis. Hyperbaric oxygen (HBO) treatment has for centuries been used to improve or cure disorders involving hypoxia and ischemia, by enhancing the amount of dissolved oxygen in the plasma and thereby increasing O₂ delivery to the tissue. Studies on HBO and cancer have up to recently focused on whether enhanced oxygen acts as a cancer promoter or not. As oxygen is believed to be required for all the major processes of wound healing, one feared that the effects of HBO would be applicable to cancer tissue as well and promote cancer growth. Furthermore, one also feared that exposing patients who had been treated for cancer, to HBO, would lead to recurrence. Nevertheless, two systematic reviews on HBO and cancer have concluded that the use of HBO in patients with malignancies is considered safe. To supplement the previous reviews, we have summarized the work performed on HBO and cancer in the period 2004–2012. Based on the present as well as previous reviews, there is no evidence indicating that HBO neither acts as a stimulator of tumor growth nor as an enhancer of recurrence. On the other hand, there is evidence that implies that HBO might have tumor-inhibitory effects in certain cancer subtypes, and we thus strongly believe that we need to expand our knowledge on the effect and the mechanisms behind tumor oxygenation.

Closure of laryngectomy defects in the age of chemoradiation therapy

The use of chemoradiation therapy in laryngeal cancer has resulted in significant reconstructive challenges. Although reconstruction of salvage laryngectomy defects remains controversial, current literature supports aggressive management of these defects with vascularized tissue, even when there is sufficient pharyngeal tissue present for primary closure. Significant advancement in reconstructive techniques has permitted improved outcomes in patients with advanced disease who require total laryngopharyngectomy or total laryngoglossectomy. Use of enteric and fasciocutaneous flaps result in good patient outcomes. Finally, wound complication rates after salvage surgery approach 60% depending on comorbid conditions such as cardiac insufficiency, hypothyroidism, or extent of previous treatment. Neck dehiscence, great vessel exposure, fistula formation, or cervical skin necrosis results in complex wounds that can often be treated initially with negative pressure dressings followed by definitive reconstruction. The timing of repair and approach to the vessel-depleted neck also present challenges in this patient population. Currently, there is significant institutional bias in the management of the patient with postchemoradiation salvage laryngectomy. Future prospective multi-institutional studies are certainly needed to more clearly define optimal treatment of these difficult patients.

Hyperbaric oxygen therapy for late radiation-associated tissue necroses: is it safe in patients with locoregionally recurrent and then successfully salvaged head-and-neck cancers?

PURPOSE

To test, in a retrospective matched-pair study, whether necrosis-rescuing hyperbaric oxygen therapy (HBOT) increases the risk of cancer re-recurrence in patients with locoregionally recurrent and then successfully salvaged head-and-neck cancers.

METHODS AND MATERIALS

Between January 1995 and July 2004, we retrospectively identified 22 patients with locoregionally recurrent and then successfully salvaged head-and-neck cancers. We defined two groups: the HBOT group, 11 patients with HBOT for rescuing late radiation-associated tissue necroses; and the non-HBOT group, the other 11 matched-pair patients without HBOT. Between the two groups, the following four factors were matched for case pairing: primary cancer subsite, initial cancer stage, age, and gender.

RESULTS

Three findings indicate that HBOT increases the risk of cancer re-recurrence. First, we observed more cancer re-recurrences in the HBOT group than in the non-HBOT group: 9 of 11 vs. 4 of 11, with 5-year disease-free survival rates after salvage of 32.7% vs. 70.0% (hazard ratio 3.2; 95% confidence interval 1.03-10.7; p = 0.048). Second, re-recurrences developed rapidly after HBOT in 6 patients. Third, 3 patients had unusual cancer re-recurrences after HBOT. Remarkably, of 9 patients with cancer re-recurrences in the HBOT group, 4 patients had cancer disease-free intervals of 9 months or less before HBOT.

CONCLUSIONS

Necrosis-rescuing HBOT should be given with caution in patients with locoregionally recurrent and then successfully salvaged head-and-neck cancers; if it cannot be omitted entirely, deferring HBOT 9 months or longer after cancer re-treatment may be prudent.

Dynamics of tumor hypoxia measured with bioreductive hypoxic cell markers

Hypoxic cells are common in tumors and contribute to malignant progression, distant metastasis and resistance to radiotherapy. It is well known that tumors are heterogeneous with respect to the levels and duration of hypoxia. Several strategies, including high-oxygen-content gas breathing, radiosensitizers and hypoxic cytotoxins, have been developed to overcome hypoxia-mediated radioresistance. However, with these strategies, an increased tumor control rate is often accompanied by more severe side effects. Consequently, development of assays for prediction of tumor response and early monitoring of treatment responses could reduce both over- and undertreatment, thereby avoiding unnecessary side effects. The purpose of this review is to discuss different assays for measurement of hypoxia that can be used to detect changes in oxygen tension. The main focus is on exogenous bioreductive hypoxia markers (2-nitroimidazoles) such as pimonidazole, CCI-103F, EF5 and F-misonidazole. These are specifically reduced and bind to macromolecules in viable hypoxic cells. A number of these bioreductive drugs are approved for clinical use and can be detected with methods ranging from noninvasive PET imaging (low resolution) to microscopic imaging of tumor sections (high resolution). If the latter are stained for multiple markers, hypoxia can be analyzed in relation to different microenvironmental parameters such as vasculature, proliferation and endogenous hypoxia-related markers, for instance HIF1alpha and CA-IX. In addition, temporal and spatial changes in hypoxia can be analyzed by consecutive injection of two different hypoxia markers. Therefore, bioreductive exogenous hypoxia markers are promising as tools for development of predictive assays or as tools for early treatment monitoring and validation of potential endogenous hypoxia markers.

Hyperbaric oxygen therapy for malignancy: a review

One unique feature of tumors is the presence of hypoxic regions, which occur predominantly at the tumor center. Hypoxia has a major impact on various aspects of tumor cell function and proliferation. Hypoxic tumor cells are relatively insensitive to conventional therapy owing to cellular adaptations effected by the hypoxic microenvironment. Recent efforts have aimed to alter the hypoxic state and to reverse these adaptations to improve treatment outcome. One way to increase tumor oxygen tensions is by hyperbaric oxygen (HBO) therapy. HBO therapy can influence the tumor microenvironment at several levels. It can alter tumor hypoxia, a potent stimulus that drives angiogenesis. Hyperoxia as a result of HBO also produces reactive oxygen species, which can damage tumors by inducing excessive oxidative stress. This review outlines the importance of oxygen to tumors and the mechanisms by which tumors survive under hypoxic conditions. It also presents data from both experimental and clinical studies for the effect of HBO on malignancy.