Oncologists and applied mathematicians are interested in understanding the dynamics of cancer-immune interactions, mainly due to the unpredictable nature of tumour cell proliferation. In this regard, mathematical modelling offers a promising approach to comprehend this potentially harmful aspect of cancer biology. This paper presents a novel dynamical model that incorporates the interactions between tumour cells, healthy tissue cells, and immune-stimulated cells when subjected to simultaneous chemotherapy and radiotherapy for treatment. We analysed the equilibria and investigated their local stability behaviour. We also study transcritical, saddle-node, and Hopf bifurcations analytically and numerically. We derive the stability and direction conditions for periodic solutions. We identify conditions that lead to chaotic dynamics and rigorously demonstrate the existence of chaos. Furthermore, we formulated an optimal control problem that describes the dynamics of tumour-immune interactions, considering treatments such as radiotherapy and chemotherapy as control parameters. Our goal is to utilize optimal control theory to reduce the cost of radiotherapy and chemotherapy, minimize the harmful effects of medications on the body, and mitigate the burden of cancer cells by maintaining a sufficient population of healthy cells. Cost-effectiveness analysis is employed to identify the most economical strategy for reducing the disease burden. Additionally, we conduct a Latin hypercube sampling-based uncertainty analysis to observe the impact of parameter uncertainties on tumour growth, followed by a sensitivity analysis. Numerical simulations are presented to elucidate how dynamic behaviour of model is influenced by changes in system parameters. The numerical results validate the analytical findings and illustrate that a multi-therapeutic treatment plan can effectively reduce tumour burden within a given time frame of therapeutic intervention.

Platinum-based concurrent chemoradiation (CCRT) improves locoregional control and overall survival of locoregionally advanced (LA) squamous cell carcinoma of the head and neck (SCCHN) when compared to radiotherapy alone, but this approach is hampered by significant toxicity. Therefore, alternative ways to enhance the radiation effects are worth investigating. Gemcitabine (2',2'-difluorodeoxycytidine), in addition to its activity against a variety of solid tumors, including SCCHN, is one of the most potent radiosensitizers, and it has an overall favorable safety profile. In this paper, the clinical experience with gemcitabine-based chemoradiation in the treatment of patients with LA-SCCHN is reviewed.

We conducted a review of the literature on the clinical experience with radiotherapy combined with either single-agent gemcitabine or gemcitabine/cisplatin-based polychemotherapy for the treatment of patients with LA-SCCHN. We also searched abstracts in databases of major international oncology meetings from the last 20 years. A meta-analysis was performed to calculate pooled proportions with 95% confidence intervals (CIs) for complete response rate and grade 3-4 acute mucositis rate.

A total of 13 papers were eligible for the literature review. For schedules using a gemcitabine dose intensity (DI) below 50 mg/m(2) per week, the complete response rate was 86% (95% CI, 74%-93%) with grade 3-4 acute mucositis rate of 38% (95% CI, 27%-50%) and acceptable late toxicity. In one of the studies employing such low DIs, survival data were provided showing a 3-year overall survival of 50%. Compared with DI ≥50 mg/m(2) per week, there was no difference in the complete response rate (71%; 95% CI, 55%-83%; p = .087) but a significantly higher (p < .001) grade 3-4 acute mucositis rate of 74% (95% CI, 62%-83%), often leading to treatment interruptions (survival data provided in 8 studies; 3-year overall survival, 27%-63%). Late toxicity comprising mainly dysphagia was generally underreported, whereas information about xerostomia and skin fibrosis was scarce.

This review highlights the radiosensitizing potential of gemcitabine and suggests that even very low dosages (less than 50 mg/m(2) per week) provide a sufficient therapeutic ratio and therefore should be further investigated. Refinements in radiation schemes, including intensity-modulated radiation therapy, in combination with low-dose gemcitabine and targeted agents, such as cetuximab, are currently being investigated.

Cisplatin-based concurrent chemoradiation (CCRT) has become the standard treatment of locally advanced head and neck cancer (LAHNC). This approach is hampered by significant toxicity. This paper reviews the studies using gemcitabine as an alternative radio-sensitizer for CCRT in patients with LAHNC. In this capacity, despite its mild intrinsic toxicity, gemcitabine comes with high rates of severe mucositis when used in dosages exceeding 50 mg/m(2) per week. CCRT with low-dose gemcitabine provides a sufficient therapeutic ratio, combining clinical activity, similar to the higher-dose regimens, with lower toxicity. Further investigation is warranted.

A prospective 1-year follow-up study in ear, nose, and throat (ENT) cancer patients was carried out one year after radiotherapy to assess the effect of varying consumption of ω3 fatty acid according to whether they consumed more or less than the 50th percentile of ω3 fatty acids. Clinical, analytical, inflammatory (CRP and IL-6), and oxidative variables (TAC, GPx, GST, and SOD) were evaluated. The study comprised 31 patients (87.1% men), with a mean age of 61.3 ± 9.1 years. Hematological variables showed significant differences in the patients with a lower consumption of ω3 fatty acids. A lower mortality and longer survival were found in the group with ω3 fatty acid consumption ≥50th percentile but the differences were not significant. No significant difference was reached in toxicity, inflammation, and oxidative stress markers. The group with ω3 fatty acid consumption <50th percentile significantly experienced more hematological and immune changes.

Radiation therapy is an essential treatment for head and neck cancer. However, the condition of the operative field is entirely altered after radiation therapy. This study aimed to examine the effects of preoperative radiation therapy on complications in patients who underwent head and neck reconstruction with flaps.

We retrospectively reviewed 252 instances of head and neck reconstruction with flaps in 240 patients between October 2000 and May 2011 at Okayama University Hospital. Of the participants, 51 had preoperative radiation exposure (21.3%) and 189 had no radiation exposure (78.7%). Postoperative complications were divided into three categories: minor complications that healed with conservative medical treatment within 4 weeks without a need for surgery; major complications requiring reoperation within 1 week after surgery (reoperation); and major complications needing additional operation later than 1 week after surgery (additional operation).

Preoperative radiation therapy was only associated with major complications requiring reoperation later than 1 week after surgery (P < 0.001), open cervical wounds (P = 0.0030), and skin grafting for cervical skin necrosis (P = 0.0031) when compared to no radiation exposure. The results of flap failure were not significantly different between both groups (P = 0.3820).

Minor complications and reoperation in the early postoperative period were not influenced by radiation exposure. The complications of radiation tend to be protracted and associated with additional operation later than 1 week after the initial surgery. It was thought that shortening of the duration of treatment was successful when we needed to perform early additional operations.