Chemoradiotherapy Combined With Intracavitary Hyperthermia for Anal Cancer

Impact of dose escalation on colostomy-free survival and treatment outcome in squamous cell anal carcinoma

PURPOSE

Primary radiochemotherapy (RCT) constitutes the standard of care for early- and advanced-stage anal carcinoma. This retrospective study investigates the impact of dose escalation on colostomy-free survival (CFS), overall survival (OS), locoregional control (LRC), progression-free survival (PFS), and acute and late toxicities in patients with squamous cell anal cancer.

METHODS

Considered were the outcomes of 87 patients with anal cancer treated with radiation/RCT between May 2004 and January 2020 at our institution. Toxicities were evaluated according to the Common Terminology Criteria for Adverse Events (CTCAE version 5.0).

RESULTS

The 87 patients received treatment with a median boost of 63 Gy to the primary tumor. With a median follow-up of 32 months, the 3‑year CFS, OS, LRC, and PFS were 79.5%, 71.4%, 83.9%, and 78.5%, respectively. Tumor relapse occurred in 13 patients (14.9%). Dose escalation to > 63 Gy (maximum 66.6 Gy) to the primary tumor in 38/87 patients revealed a nonsignificant trend for improved 3‑year CFS (82.4% vs. 97%, P = 0.092), a significantly improved CFS for T2/T3 tumors (72.6% vs. 100%, P = 0.008), and a significantly improved 3‑year PFS for T1/T2 tumors (76.7% vs. 100%, P = 0.035). While acute toxicities did not differ, dose escalation > 63 Gy led to a higher rate of chronic skin toxicities (43.8% vs. 69%, P = 0.042). Treatment with intensity-modulated radiotherapy (IMRT) showed a significant improvement in 3‑year OS (75.4% vs. 53.8%, P = 0.048). In multivariate analysis, significant improvements for T1/T2 tumors (CFS, OS, LRC, PFS), G1/2 tumors (PFS), and IMRT (OS) were shown. The nonsignificant trend for CFS improvement with dose escalation > 63 Gy was also apparent in multivariate analysis (P = 0.067).

CONCLUSION

Dose escalation > 63 Gy (maximum 66.6 Gy) may improve CFS and PFS for certain subgroups, with a concomitant increase in chronic skin toxicities. Modern IMRT seems to be associated with an improvement in OS.

RNA methylation and cellular response to oxidative stress-promoting anticancer agents

Disruption of the complex network that regulates redox homeostasis often underlies resistant phenotypes, which hinder effective and long-lasting cancer eradication. In addition, the RNA methylome-dependent control of gene expression also critically affects traits of cellular resistance to anti-cancer agents. However, few investigations aimed at establishing whether the epitranscriptome-directed adaptations underlying acquired and/or innate resistance traits in cancer could be implemented through the involvement of redox-dependent or -responsive signaling pathways. This is unexpected mainly because: i) the effectiveness of many anti-cancer approaches relies on their capacity to promote oxidative stress (OS); ii) altered redox milieu and reprogramming of mitochondrial function have been acknowledged as critical mediators of the RNA methylome-mediated response to OS. Here we summarize the current state of understanding on this topic, as well as we offer new perspectives that might lead to original approaches and strategies to delay or prevent the problem of refractory cancer and tumor recurrence.

The Emerging Evidence Supporting Integration of Deep Regional Hyperthermia With Chemoradiation in Bladder Cancer

For decades, the antineoplastic potential of hyperthermia alone or in combination with radiotherapy and/or chemotherapy has been subject of intensive preclinical and clinical research in various tumor entities. The clinical evidence on the beneficial effects of additional hyperthermia in combination with intravesical Mitomycin C for superficial non-muscle-invasive bladder cancer as well as for deep regional microwave hyperthermia techniques applied during an external beam radiotherapy or chemoradiation treatment for more advanced tumors are summarized. In some series, deep regional hyperthermia in combination with an initial transurethral resection and Cisplatin-based chemoradiation increased the 5-year overall survival rates up to 20%. The presented data justifies a fresh irrespective chance for mild regional hyperthermia in the context of new progressive prospective trials on multimodality treatment for bladder preservation.

Integrating Loco-Regional Hyperthermia Into the Current Oncology Practice: SWOT and TOWS Analyses

Moderate hyperthermia at temperatures between 40 and 44°C is a multifaceted therapeutic modality. It is a potent radiosensitizer, interacts favorably with a host of chemotherapeutic agents, and, in combination with radiotherapy, enforces immunomodulation akin to “in situ tumor vaccination.” By sensitizing hypoxic tumor cells and inhibiting repair of radiotherapy-induced DNA damage, the properties of hyperthermia delivered together with photons might provide a tumor-selective therapeutic advantage analogous to high linear energy transfer (LET) neutrons, but with less normal tissue toxicity. Furthermore, the high LET attributes of hyperthermia thermoradiobiologically are likely to enhance low LET protons; thus, proton thermoradiotherapy would mimic ¹²C ion therapy. Hyperthermia with radiotherapy and/or chemotherapy substantially improves therapeutic outcomes without enhancing normal tissue morbidities, yielding level I evidence reported in several randomized clinical trials, systematic reviews, and meta-analyses for various tumor sites. Technological advancements in hyperthermia delivery, advancements in hyperthermia treatment planning, online invasive and non-invasive MR-guided thermometry, and adherence to quality assurance guidelines have ensured safe and effective delivery of hyperthermia to the target region. Novel biological modeling permits integration of hyperthermia and radiotherapy treatment plans. Further, hyperthermia along with immune checkpoint inhibitors and DNA damage repair inhibitors could further augment the therapeutic efficacy resulting in synthetic lethality. Additionally, hyperthermia induced by magnetic nanoparticles coupled to selective payloads, namely, tumor-specific radiotheranostics (for both tumor imaging and radionuclide therapy), chemotherapeutic drugs, immunotherapeutic agents, and gene silencing, could provide a comprehensive tumor-specific theranostic modality akin to “magic (nano)bullets.” To get a realistic overview of the strength (S), weakness (W), opportunities (O), and threats (T) of hyperthermia, a SWOT analysis has been undertaken. Additionally, a TOWS analysis categorizes future strategies to facilitate further integration of hyperthermia with the current treatment modalities. These could gainfully accomplish a safe, versatile, and cost-effective enhancement of the existing therapeutic armamentarium to improve outcomes in clinical oncology.

Recent technological advancements in radiofrequency- andmicrowave-mediated hyperthermia for enhancing drug delivery

Hyperthermia therapy is a potent enhancer of chemotherapy and radiotherapy. In particular, microwave (MW) and radiofrequency (RF) hyperthermia devices provide a variety of heating approaches that can treat most cancers regardless the size. This review introduces the physics of MW/RF hyperthermia, the current state-of-the-art systems for both localized and regional heating, and recent advancements in hyperthermia treatment guidance using real-time computational simulations and magnetic resonance thermometry. Clinical trials involving RF/MW hyperthermia as adjuvant for chemotherapy are also presented per anatomical site. These studies favor the use of adjuvant hyperthermia since it significantly improves curative and palliative clinical outcomes. The main challenge of hyperthermia is the distribution of state-of-the-art heating systems. Nevertheless, we anticipate that recent technology advances will expand the use of hyperthermia to chemotherapy centers for enhanced drug delivery. These new technologies hold great promise not only for (image-guided) perfusion modulation and sensitization for cytotoxic drugs, but also for local delivery of various compounds using thermosensitive liposomes.

Improved treatment outcome and lower skin toxicity with intensity-modulated radiotherapy vs. 3D conventional radiotherapy in anal cancer

PURPOSE

Radiochemotherapy is the standard treatment for anal carcinoma (ACa). Intensity-modulated radiotherapy (IMRT) has been introduced, allowing focused irradiation of the tumor area. Whether physical benefits of IMRT translate to clinical benefits has not been sufficiently demonstrated.

METHODS

We retrospectively reviewed data from 82 patients with newly diagnosed ACa. Patients treated with IMRT were compared with previous patients treated with conventional three-dimensional computational radiotherapy (3D-CRT). The influence of IMRT on complete remission and acute and chronic side effects was analyzed in univariate and multivariate analyses.

RESULTS

39/40 patients treated with IMRT were in complete remission after 1 year compared to 31/39 patients treated with 3D-CRT (p = 0.014). Multivariate analysis confirmed tumor T stage as well as lack of IMRT treatment as risk factors for persistent tumor at 6 months. No significant benefits of IMRT were apparent at later timepoints (median follow up 52 months, IQR: 31.5-71.8 months). Patients treated with IMRT had a significantly lower degree of skin toxicity (median 2 vs. 3 in a scale ranging from 0 to 3, p = 0.00092). Rates of hematological toxicity/proctitis were not reduced and rates of acute diarrhea increased (p = 0.034). Median length of hospitalization tended to be shorter in patients treated with IMRT (n. s.).

CONCLUSION

We present a real-world experience of shifting radiation technique from conventional 3D-CRT to IMRT. IMRT patients had better tumor control at 1 year and lower degrees of skin toxicity. Our data indicate that IMRT can enable therapies with lower side effects with equal or better oncological results for patients with ACa.

Therapeutic hyperthermia

The term hyperthermia broadly refers to either an abnormally high fever or the treatment of a disease by the induction of fever. Its effect depends on the temperature and exposure time. The increasing number of applications and clinical trials at universities, clinics, and hospitals prove the feasibility and applicability of clinical therapeutic hyperthermia. This chapter aims to outline and discuss the means by which electromagnetic energy and other techniques can provide elevation of temperature within the human body. Because of the individual characteristic of each type of treatment, different modalities of heating systems have evolved. The chapter concludes with a discussion of challenges and opportunities for further improvement in technology and routine clinical application.

Thermal combination therapies for local drug delivery by magnetic resonance-guided high-intensity focused ultrasound

Several thermal-therapy strategies such as thermal ablation, hyperthermia-triggered drug delivery from temperature-sensitive liposomes (TSLs), and combinations of the above were investigated in a rhabdomyosarcoma rat tumor model (n = 113). Magnetic resonance-guided high-intensity focused ultrasound (MR-HIFU) was used as a noninvasive heating device with precise temperature control for image-guided drug delivery. For the latter, TSLs were prepared, coencapsulating doxorubicin (dox) and [Gd(HPDO3A)(H₂O)], and injected in tumor-bearing rats before MR-HIFU treatment. Four treatment groups were defined: hyperthermia, ablation, hyperthermia followed by ablation, or no HIFU. The intratumoral TSL and dox distribution were analyzed by single-photon emission computed tomography (SPECT)/computed tomography (CT), autoradiography, and fluorescence microscopy. Dox biodistribution was quantified and compared with that of nonliposomal dox. Finally, the treatment efficacy of all heating strategies plus additional control groups (saline, free dox, and Caelyx) was assessed by tumor growth measurements. All HIFU heating strategies combined with TSLs resulted in cellular uptake of dox deep into the interstitial space and a significant increase of tumor drug concentrations compared with a treatment with free dox. Ablation after TSL injection showed [Gd(HPDO3A)(H₂O)] and dox release along the tumor rim, mirroring the TSL distribution pattern. Hyperthermia either as standalone treatment or before ablation ensured homogeneous TSL, [Gd(HPDO3A)(H₂O)], and dox delivery across the tumor. The combination of hyperthermia-triggered drug delivery followed by ablation showed the best therapeutic outcome compared with all other treatment groups due to direct induction of thermal necrosis in the tumor core and efficient drug delivery to the tumor rim.

Planning, optimisation and evaluation of hyperthermia treatments

BACKGROUND

Hyperthermia treatment planning using dedicated simulations of power and temperature distributions is very useful to assist in hyperthermia applications. This paper describes an advanced treatment planning software package for a wide variety of applications.

METHODS

The in-house developed C++ software package Plan2Heat runs on a Linux operating system. Modules are available to perform electric field and temperature calculations for many heating techniques. The package also contains optimisation routines, post-treatment evaluation tools and a sophisticated thermal model enabling to account for 3D vasculature based on an angiogram or generated artificially using a vessel generation algorithm. The use of the software is illustrated by a simulation of a locoregional hyperthermia treatment for a pancreatic cancer patient and a spherical tumour model heated by interstitial hyperthermia, with detailed 3D vasculature included.

RESULTS

The module-based set-up makes the software flexible and easy to use. The first example demonstrates that treatment planning can help to focus the heating to the tumour. After optimisation, the simulated absorbed power in the tumour increased with 50%. The second example demonstrates the impact of accurately modelling discrete vasculature. Blood at body core temperature entering the heated volume causes relatively cold tracks in the heated volume, where the temperature remains below 40 °C.

CONCLUSIONS

A flexible software package for hyperthermia treatment planning has been developed, which can be very useful in many hyperthermia applications. The object-oriented structure of the source code allows relatively easy extension of the software package with additional tools when necessary for future applications.

Combinations in multimodality treatments and clinical outcomes during cancer

Combination approach could be easily considered as the future of therapeutics in all pathological states including cancer. Scientists are trying different combinations in order to determine synergism among different therapeutics which ultimately helps in the improved and more efficient management of the affected patients. Combination of multi-chemotherapeutic agents, or multi-drug therapy, may be the most commonly used strategy for cancer treatment. Monotherapy causes drug resistance and loses its response in patients after several cycles of treatment. While combining different anticancer drugs together for cancer treatment, as in the case of the cocktail therapy for HIV, not only overcomes the drug resistance but also leads to a synergistic effect, therefore showing prolonged survival for patients. The present review article is focused on different combinations in use for better efficiency of therapeutics against cancer. We searched the electronic database PubMed for pre-clinical as well as clinical controlled trials reporting diagnostic as well as therapeutic advances of various combinations in cancer. It was observed clearly that combination approach is better in various aspects including increase in efficacy, specificity and decline in the unwanted side effects.

Inhibition of mTOR promotes hyperthermia sensitivity in SMMC-7721 human hepatocellular carcinoma cell line

The mammalian target of rapamycin (mTOR) is a critical mediator of the phosphoinositide 3-kinase/protein kinase B/mTOR signaling pathway, and mTOR activity is induced following heat shock. Thermotherapy is used to treat hepatocellular carcinoma (HCC). However, the role of mTOR in modulating thermosensitivity in HCC has yet to be elucidated. In the present study, the antisense plasmid pEGFP-C1-mTOR was transfected into SMMC-7721 cells, and the expression levels of mTOR were analyzed by reverse transcription-polymerase chain reaction and western blot analysis. The thermal responses of the transfected cells were also examined. The results revealed that SMMC-7721 cells were sensitive to heat treatment, and cell viability was significantly inhibited following hyperthermia treatment (P<0.01). The mRNA and protein expression levels of mTOR decreased post-transfection. Cell proliferation, colony-forming ability and motility were all significantly decreased following hyperthermia treatment in the transfected cells. Flow cytometry analysis demonstrated that apoptosis was significantly increased following treatment (P<0.01). The number of cells in S phase was increased, and the cell cycle was arrested in S phase. In conclusion, inhibition of mTOR increased the thermosensitivity of SMMC-7721 cells by increasing cellular apoptosis and inducing S phase arrest.

Local hyperthermia combined with radiotherapy and-/or chemotherapy: recent advances and promises for the future

Hyperthermia, one of the oldest forms of cancer treatment involves selective heating of tumor tissues to temperatures ranging between 39 and 45°C. Recent developments based on the thermoradiobiological rationale of hyperthermia indicate it to be a potent radio- and chemosensitizer. This has been further corroborated through positive clinical outcomes in various tumor sites using thermoradiotherapy or thermoradiochemotherapy approaches. Moreover, being devoid of any additional significant toxicity, hyperthermia has been safely used with low or moderate doses of reirradiation for retreatment of previously treated and recurrent tumors, resulting in significant tumor regression. Recent in vitro and in vivo studies also indicate a unique immunomodulating prospect of hyperthermia, especially when combined with radiotherapy. In addition, the technological advances over the last decade both in hardware and software have led to potent and even safer loco-regional hyperthermia treatment delivery, thermal treatment planning, thermal dose monitoring through noninvasive thermometry and online adaptive temperature modulation. The review summarizes the outcomes from various clinical studies (both randomized and nonrandomized) where hyperthermia is used as a thermal sensitizer of radiotherapy and-/or chemotherapy in various solid tumors and presents an overview of the progresses in loco-regional hyperthermia. These recent developments, supported by positive clinical outcomes should merit hyperthermia to be incorporated in the therapeutic armamentarium as a safe and an effective addendum to the existing oncological treatment modalities.

Pifithrin-μ, an inhibitor of heat-shock protein 70, can increase the antitumor effects of hyperthermia against human prostate cancer cells

Hyperthermia (HT) improves the efficacy of anti-cancer radiotherapy and chemotherapy. However, HT also inevitably evokes stress responses and increases the expression of heat-shock proteins (HSPs) in cancer cells. Among the HSPs, HSP70 is known as a pro-survival protein. In this study, we investigated the sensitizing effect of pifithrin (PFT)-μ, a small molecule inhibitor of HSP70, when three human prostate cancer cell lines (LNCaP, PC-3, and DU-145) were treated with HT (43°C for 2 h). All cell lines constitutively expressed HSP70, and HT further increased its expression in LNCaP and DU-145. Knockdown of HSP70 with RNA interference decreased the viability and colony-forming ability of cancer cells. PFT-μ decreased the viabilities of all cell lines at one-tenth the dose of Quercetin, a well-known HSP inhibitor. The combination therapy with suboptimal doses of PFT-μ and HT decreased the viability of cancer cells most effectively when PFT-μ was added immediately before HT, and this combination effect was abolished by pre-knockdown of HSP70, suggesting that the effect was mediated via HSP70 inhibition. The combination therapy induced cell death, partially caspase-dependent, and decreased proliferating cancer cells, with decreased expression of c-Myc and cyclin D1 and increased expression of p21^WAF1/Cip, indicating arrest of cell growth. Additionally, the combination therapy significantly decreased the colony-forming ability of cancer cells compared to therapy with either alone. Furthermore, in a xenograft mouse model, the combination therapy significantly inhibited PC-3 tumor growth. These findings suggest that PFT-μ can effectively enhance HT-induced antitumor effects via HSP70 inhibition by inducing cell death and arrest of cell growth, and that PFT-μ is a promising agent for use in combination with HT to treat prostate cancer.

Unexpected functions of tRNA and tRNA processing enzymes

tRNA and tRNA processing enzymes impact more than protein production. Studies have uncovered roles for tRNA in the regulation of transcription, translation and protein turnover. Induced by stress or as a programmed part of development, nonrandom tRNA fragments can guide mRNA cleavage, inhibit translation and promote morphological changes. Similarly, tRNA processing enzymes, such as RNaseP and tRNA aminoacyl-synthetases participate in tasks affecting more than tRNA function (i.e., mRNA function and cellular signaling). Unraveling the complexities of their functions will increase our understanding of how mutations associated with disease impact these functions and the downstream consequences. This chapter focuses on how tRNA and tRNA processing enzymes influence cellular function and RNA-infrastructure via pathways beyond the decoding activities that tRNA are known for.

Activation of caspase-9, but not caspase-2 or caspase-8, is essential for heat-induced apoptosis in Jurkat cells

Exposure of cells to hyperthermia is known to induce apoptosis, although the underlying mechanisms are only partially understood. Here, we examine the molecular requirements necessary for heat-induced apoptosis using genetically modified Jurkat T-lymphocytes. Cells stably overexpressing Bcl-2/Bcl-x(L) or stably depleted of Apaf-1 were completely resistant to heat-induced apoptosis, implicating the involvement of the mitochondria-mediated pathway. Pretreatment of wild-type cells with the cell-permeable biotinylated general caspase inhibitor b-VAD-fmk (biotin-Val-Ala-Asp(OMe)-CH(2)F) both inhibited heat-induced apoptosis and affinity-labeled activated initiator caspase-2, -8, and -9. Despite this finding, however, cells engineered to be deficient in caspase-8, caspase-2, or the caspase-2 adaptor protein RAIDD (receptor-interacting protein (RIP)-associated Ich-1/CED homologous protein with death domain) remained susceptible to heat-induced apoptosis. Additionally, b-VAD-fmk failed to label any activated initiator caspase in Apaf-1-deficient cells exposed to hyperthermia. Cells lacking Apaf-1 or the pro-apoptotic BH3-only protein Bid exhibited lower levels of heat-induced Bak activation, cytochrome c release, and loss of mitochondrial membrane potential, although cleavage of Bid to truncated Bid (tBid) occurred downstream of caspase-9 activation. Combined, the data suggest that caspase-9 is the critical initiator caspase activated during heat-induced apoptosis and that tBid may function to promote cytochrome c release during this process as part of a feed-forward amplification loop.

Randomized clinical trials in rectal and anal cancers

This article reviews randomized clinical trials (RCTs) published between April 2001 and November 2008 on the management of patients with rectal cancer. In total, the authors reviewed 78 RCTs on therapy for rectal cancer. Of these, five met the authors' criteria for level 1a evidence. The article discusses the major RCTs and relevant findings that have impacted clinical management most and includes most but not all RCTs on therapy for rectal cancer published during this period.

Endocavitary thermal therapy by MRI-guided phased-array contact ultrasound: experimental and numerical studies on the multi-input single-output PID temperature controller's convergence and stability

PURPOSE

Endocavitary high intensity contact ultrasound (HICU) may offer interesting therapeutic potential for fighting localized cancer in esophageal or rectal wall. On-line MR guidance of the thermotherapy permits both excellent targeting of the pathological volume and accurate preoperatory monitoring of the temperature elevation. In this article, the authors address the issue of the automatic temperature control for endocavitary phased-array HICU and propose a tailor-made thermal model for this specific application. The convergence and stability of the feedback loop were investigated against tuning errors in the controller's parameters and against input noise, through ex vivo experimental studies and through numerical simulations in which nonlinear response of tissue was considered as expected in vivo.

METHODS

An MR-compatible, 64-element, cooled-tip, endorectal cylindrical phased-array applicator of contact ultrasound was integrated with fast MR thermometry to provide automatic feedback control of the temperature evolution. An appropriate phase law was applied per set of eight adjacent transducers to generate a quasiplanar wave, or a slightly convergent one (over the circular dimension). A 2D physical model, compatible with on-line numerical implementation, took into account (1) the ultrasound-mediated energy deposition, (2) the heat diffusion in tissue, and (3) the heat sink effect in the tissue adjacent to the tip-cooling balloon. This linear model was coupled to a PID compensation algorithm to obtain a multi-input single-output static-tuning temperature controller. Either the temperature at one static point in space (situated on the symmetry axis of the beam) or the maximum temperature in a user-defined ROI was tracked according to a predefined target curve. The convergence domain in the space of controller's parameters was experimentally explored ex vivo. The behavior of the static-tuning PID controller was numerically simulated based on a discrete-time iterative solution of the bioheat transfer equation in 3D and considering temperature-dependent ultrasound absorption and blood perfusion.

RESULTS

The intrinsic accuracy of the implemented controller was approximately 1% in ex vivo trials when providing correct estimates for energy deposition and heat diffusivity. Moreover, the feedback loop demonstrated excellent convergence and stability over a wide range of the controller's parameters, deliberately set to erroneous values. In the extreme case of strong underestimation of the ultrasound energy deposition in tissue, the temperature tracking curve alone, at the initial stage of the MR-controlled HICU treatment, was not a sufficient indicator for a globally stable behavior of the feedback loop. Our simulations predicted that the controller would be able to compensate for tissue perfusion and for temperature-dependent ultrasound absorption, although these effects were not included in the controller's equation. The explicit pattern of acoustic field was not required as input information for the controller, avoiding time-consuming numerical operations.

CONCLUSIONS

The study demonstrated the potential advantages of PID-based automatic temperature control adapted to phased-array MR-guided HICU therapy. Further studies will address the integration of this ultrasound device with a miniature RF coil for high resolution MRI and, subsequently, the experimental behavior of the controller in vivo.

Concomitant hyperthermia and radiation therapy for treating locally advanced rectal cancer

BACKGROUND

Surgery has been the treatment of choice for patients with rectal cancer. For locally advanced cancer results were poor, with high rates of locoregional recurrences and poor overall survival data. Adding (chemo)radiotherapy upfront improved results mainly in locoregional control. Adding hyperthermia to radiotherapy preoperatively might have an equivalent beneficial effect.

OBJECTIVES

To quantify the potential beneficial effect of thermo radiation compared to chemo-radiation with respect to pathological complete responses, overall survival and toxicity in rectal cancer therapy.

SEARCH STRATEGY

We identified the relevant phase II and III randomised controlled trials in any language trough electronic searches May 2007 of the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library Issue 1, 2007), the Cochrane Colorectal Cancer Groups Specialised Register, MEDLINE (from 1966), EMBASE (from 1974), CINAHL (from 1982). Furthermore, various trial databases were searched for the identification of recent completed and ongoing trials (metaRegister of Controlled Trials, Cancer Research UK, Cancer.gov, The Eastern Cooperative Oncology Group Trials Database). All studies identified until May 2007 were considered for inclusion in the present study.

SELECTION CRITERIA

Only phase II and III randomised controlled clinical trials were included in the analysis.

DATA COLLECTION AND ANALYSIS

All identified studies were assessed by two independent reviewers. A weighted estimate of the treatment effect was computed for 2, 3, 4 and 5-year survival, for local tumour recurrence, severe acute and late toxicity and complete tumour response (CR). CR was defined either clinically by disappearance of all pretreatment signs of local tumour or pathologically by microscopically free margins. The risk ratio (RR) and hazard ratio (HR) were used. Analyses were performed with the Reference Manager (RevMan).

MAIN RESULTS

Six RCTs published between 1990 and 2007 were identified. A total number of 520 patients was treated, 258 in the radiotherapy only arm (RT) and 262 in the radiotherapy-hyperthermia arm (RHT). Four studies (424 patients) reported overall survival (OS) rates. After 2 years, OS was significantly better in the RHT group (HR 2.06; 95% CI 1.33-3.17; p=.001), but this difference disappeared after a longer period (3, 4 and 5 year OS). All but one studies reported CR rates. A significant higher CR rate was observed in the RHT group (RR 2.81; 95% CI 1.22-6.45; p=.01). Only 2 studies reported on acute toxicity. In these 2 studies no significant differences were observed between the RT and the RHT group. Late toxicity data were not reported.

AUTHORS' CONCLUSIONS

Further studies are needed to compare chemoradiation versus thermoradiation versus chemoradiation plus hyperthermia in well selected/conducted and quality controlled randomised trials.

Evidence that tRNA modifying enzymes are important in vivo targets for 5-fluorouracil in yeast

We have screened a collection of haploid yeast knockout strains for increased sensitivity to 5-fluorouracil (5-FU). A total of 138 5-FU sensitive strains were found. Mutants affecting rRNA and tRNA maturation were particularly sensitive to 5-FU, with the tRNA methylation mutant trm10 being the most sensitive mutant. This is intriguing since trm10, like many other tRNA modification mutants, lacks a phenotype under normal conditions. However, double mutants for nonessential tRNA modification enzymes are frequently temperature sensitive, due to destabilization of hypomodified tRNAs. We therefore tested if the sensitivity of our mutants to 5-FU is affected by the temperature. We found that the cytotoxic effect of 5-FU is strongly enhanced at 38 degrees C for tRNA modification mutants. Furthermore, tRNA modification mutants show similar synthetic interactions for temperature sensitivity and sensitivity to 5-FU. A model is proposed for how 5-FU kills these mutants by reducing the number of tRNA modifications, thus destabilizing tRNA. Finally, we found that also wild-type cells are temperature sensitive at higher concentrations of 5-FU. This suggests that tRNA destabilization contributes to 5-FU cytotoxicity in wild-type cells and provides a possible explanation why hyperthermia can enhance the effect of 5-FU in cancer therapy.

The Kadota Fund International Forum 2004--clinical group consensus

The results from experimental studies indicate that hyperthermia is both an effective complementary treatment to, and a strong sensitiser of, radiotherapy and many cytotoxic drugs. Since the first international hyperthermia conference in 1975, Washington DC, techniques to increase tumour temperature have been developed and tested clinically. Hyperthermia can be applied by several methods: local hyperthermia by external or internal energy sources, perfusion hyperthermia of organs, limbs, or body cavities, and whole body hyperthermia. The clinical value of hyperthermia in combination with other treatment modalities has been shown by randomised trials. Significant improvement in clinical outcome has been demonstrated for tumours of the head and neck, breast, brain, bladder, cervix, rectum, lung, oesophagus, for melanoma and sarcoma. The addition of hyperthermia resulted in remarkably higher (complete) response rates, accompanied by improved local tumour control rates, better palliative effects, and/or better overall survival rates. Toxicity from hyperthermia cannot always be avoided, but is usually of limited clinical relevance. In spite of these good clinical results, hyperthermia has received little attention. Problems with acceptance concern the limited availability of equipment, the lack of awareness concerning clinical results, and the lack of financial resources. In this paper the most relevant literature describing the clinical effects of hyperthermia is reviewed and discussed, and means to overcome the lack of awareness and use of this modality is described.