The use of stereotactic body radiation therapy employing few large fractions of radiation dose for the treatment of non-small cell lung cancer has been proven very successful, high values of tumour control probability (TCP) being clinically achieved. In spite of the success of the fractionation schedules currently used, there is a tendency towards reducing the number of fractions for economical and practical reasons, and also for maximizing the comfort of the patients. It is therefore the main aim of this thesis to investigate the impact of a severely reduced number of fractions on the tumour control probability for tumours that contain hypoxic areas. The impact on TCP of other factors such as hypoxic fraction, distribution of the oxygen partial pressure and location of the hypoxic volume within the tumour were also investigated. The effect of tumour motion due to breathing was included and evaluated using Cone Beam Computed Tomography (CBCT) data from patients imaged with internal markers in the liver and pancreas. The results clearly showed that in the presence of hypoxia, TCP is seriously compromised if there is not enough time for reoxygenation between fractions. A reduction in the number of fractions of just one fraction may require an increase of several Gy per fraction to obtain a similar TCP. The diaphragmatic tumour motion range showed little influence on TCP provided that the PTV encompassed all tumour positions. The dose delivered to the PTV margin was found not to be the only factor that is significant for local control, the average dose correlated better with TCP. The agreement of the results of this work with clinical results also serve as a strong indicator that inter-fraction reoxygenation is an important process in real-life patients treated with stereotactic body radiotherapy.

Abstract Reactive nitrogen species (RNS) and reactive oxygen species (ROS) have been linked with the pathogenesis of lung malignancies and chronic obstructive pulmonary disease (COPD). In vitro studies indicated that mesothelioma and lung carcinoma cell lines synthesize nitric oxide synthases (NOS) mRNA. The Comet-assay indicated that asbestos fibers caused DNA single -strand breaks in mesothelial cells, and this effect was enhanced by glutathione depletion. The use of FPG in the Comet assay indicated that the asbestos induced DNA strand breaks were oxidant mediated. In vivo non-neoplastic pleura was mostly negative for inducible NOS (iNOS), while inflamed pleura was positive. The immunohistochemical expression of iNOS was detected in 74% and 96% of malignant mesotheliomas and metastatic pleural adenocarcinomas, respectively. Epithelial and mixed mesotheliomas expressed more often intense iNOS immunoreactivity compared to the sarcomatoid subtype. Normal mesothelial cells showed occasional positivity for endothelial NOS (eNOS), but reactive mesothelial cells were strongly stained. eNOS was found in 89% of mesotheliomas. Vascular endothelial growth factor (VEGF) was identified in 47%, a VEGF receptor FLK1 in 69% and the VEGF receptor, FLT1, in 71% of mesotheliomas. FLK1 or FLT1 immunoreactivities were more often seen in epithelioid and biphasic mesotheliomas than in sarcomatoid mesotheliomas. In lung samples of non-smokers, smokers and COPD patients, the levels of nitrotyrosine were higher in alveolar macrophages of smokers and COPD patients than in the non-smokers and in the alveolar epithelium of smokers and COPD patients than in the non-smokers. The iNOS expression was weak in the bronchial and alveolar epithelium in all groups but eNOS was most prominently expressed in alveolar macrophages while neuronal NOS (nNOS) was negative in all of the major cell types of the lung. Bronchial metaplasia-dysplasia-sequence was clearly positive for iNOS, nNOS and nitrotyrosine. Thus, smoking can cause protein nitration also in normal lung. Prominent iNOS and nNOS immunoreactivity in metaplasia-dysplasia-lesions suggests a divergent role of NOSs in carcinogenesis and destruction of alveolar epithelium in emphysematous lung. In lung cancer samples, iNOS was detected in 40% cases, while 89% and 81% cases were positive for eNOS and nNOS, respectively. Intense eNOS staining was seen more often in adenocarcinomas than in squamous cells carcinomas, and iNOS immunoreactivity was seen more often in grade I-II tumors than in grade III tumors. The patients with tumors showing high expression of iNOS, eNOS and nNOS, exhibited better survival, but this was not an independent prognostic factor.

A common co-pathology of large lung tumors located near the central airways is collapse of portions of lung due to blockage of airflow by the tumor. Not only does the lung volume decrease as collapse occurs, but fluid from capillaries also fills the space no longer occupied by air, greatly altering tissue appearance. During radiotherapy, typically administered to the patient over multiple weeks, the tumor can dramatically shrink in response to the treatment, restoring airflow to the lung sections which were collapsed when therapy began. While return of normal lung function is a positive development, the change in anatomy presents problems for future radiation sessions since the treatment was planned on lung geometry which is no longer accurate. The treatment must be adapted to the new lung state so that the radiation continues to accurately target the tumor while safely avoiding healthy tissue. However, to account for the dose delivered previously, correspondences of anatomy between the former image when the lung was collapsed and the re-expanded lung in a current image must be obtained. This process, known as deformable image registration, is performed by registration software. Most registration algorithms assume that identical anatomy is contained in the images and that intensities of corresponding image elements are similar; both assumptions are untrue when collapsed lung re-expands. This work was to develop an algorithm which accurately registers images in the presence of lung expansion. The lung registration method matched CT images of patients aided by vessel enhancement and information of individual lobe boundaries. The algorithm was tested on eighteen patients with lung collapse using physician-specified correspondences to measure registration error. The image registration algorithm developed in this work which was designed for challenging lung patients resulted in accuracy comparable to that of other methods when large lung changes are absent.

Small cell lung cancer (SCLC) is an extremely aggressive disease characterized by early metastasis and acquired resistance to therapy. SCLC is distinguished by its neuroendocrine (NE) component; the role of which is not fully understood in metastasis and response to therapy. Patients respond exceptionally well to first round chemotherapy; however, relapse with therapy-resistant tumours is virtually inevitable. Hypoxic regions within tumours can contribute towards metastasis and therapy resistance, highlighting hypoxia-targeted therapy as a novel approach for improving treatment for SCLC patients. Tumours are highly phenotypically heterogeneous, raising debate over the roles played by each cell type. Analysis of NE and epithelial markers in SCLC cell lines highlighted this inter-tumour heterogeneity. Further heterogeneity is displayed in SCLC xenograft tumours that show areas of dual epithelial and NE marker expression as well as regions negative for both markers. Irradiating xenograft tumours enhanced heterogeneity of the NE marker, pro-opiomelanocortin (POMC), which is ectopically secreted by a subset of SCLC tumours. Examining changes in marker expression post-therapy could provide vital information regarding transitions that can serve to guide therapy. SCLC is a highly metastatic disease. The role of the NE phenotype in human SCLC is not fully understood, but is considered essential for metastasis in murine models. Sub-cutaneous, intravenous and intra-splenic injection were carried out and resulted in no metastasis, spontaneous tumour generation and peripheral liver tumour growth, respectively. POMC expression was present and extremely heterogeneous within the liver, suggesting that NE properties are maintained in metastases; however, further work is necessary to develop a more consistent metastatic model that can be used to assess responses to therapy in a more clinically relevant setting. SCLC tumours proliferate rapidly and outgrow their nutrient and oxygen supplies, resulting in hypoxic conditions. Here, carbonic anhydrase IX (CA IX) becomes up-regulated in order to maintain pH levels suitable for survival. The specific CA IX inhibitor, S4, induces hypoxia-specific cell death in vitro and impairs tumour growth in vivo. This response is further accentuated by combining S4 with single or repeated cisplatin doses. Combination treatment reduced gene expression of S-phase kinase-associated protein (Skp2), associated with cisplatin resistance. CA IX inhibition combined with cisplatin chemotherapy therefore presents a novel treatment for SCLC tumours that could reduce therapy resistance. In summary, heterogeneity is extremely important when choosing treatment options for SCLC and must be considered when basing treatment on single biopsies. NE and epithelial markers are present within sub-cutaneous and liver tumours; however, a reliable multi-organ metastatic model is necessary to fully appreciate the role of these markers in the spread of SCLC. Hypoxic regions within sub-cutaneous xenograft tumours upregulate CA IX. Inhibition of this enzyme resulted in impaired tumour growth, particularly when used together with cisplatin. Combining CA IX inhibition with cisplatin presents a much-needed novel therapy for SCLC.

京都大学 / 0048 / 新制・課程博士 / 博士(医学) / 甲第22005号 / 医博第4519号 / 新制||医||1038(附属図書館) / 京都大学大学院医学研究科医学専攻 / (主査)教授 平井 豊博, 教授 松原 和夫, 教授 萩原 正敏 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DFAM

京都大学 / 0048 / 新制・論文博士 / 博士(医学) / 乙第12803号 / 論医博第2075号 / 新制||医||1001(附属図書館) / 80847 / (主査)教授 伊達 洋至, 教授 武藤 学, 教授 川上 浩司 / 学位規則第4条第2項該当 / Doctor of Medical Science / Kyoto University / DFAM

京都大学 / 0048 / 新制・課程博士 / 博士(医学) / 甲第18869号 / 医博第3980号 / 新制||医||1008(附属図書館) / 31820 / 京都大学大学院医学研究科医学専攻 / (主査)教授 武田 俊一, 教授 小西 郁生, 教授 小松 賢志 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DFAM

Non-small cell lung cancer (NSCLC) makes up the majority of lung cancers, which remains the leading cause of cancer mortality worldwide. NSCLC with mutant epidermal growth factor receptor (EGFR) is currently treated with tyrosine kinase inhibitors (TKIs). TKIs have proven effective in improving survival until resistance is conferred, mostly by way of the exon 20, threonine 790 to methionine (T790M) point mutation in EGFR. The mechanism by which this point mutation arises is poorly understood. Herein we report a possible pathway by which the C to T transition that leads to T790M comes about. We show that activation-induced cytidine deaminase (AID) mRNA expression is induced upon treatment with EGFR TKIs in mutant-EGFR human lung cancer cell lines but not in control cell lines. We also show that stable expression of AID is sufficient to produce resistance to one such TKI, erlotinib, and is sufficient to produce T790M itself. We also report that B-cell lymphoma 6 (BCL6) may precede AID in this pathway. Our results show that BCL6 is upregulated in these cell lines treated with EGFR TKIs but not in normal bronchial cells. We then treated human lung cancer cell lines with EGFR TKIs in combination with BCL6 inhibitors. Our results show that AID is dependent upon BCL6 expression. Finally, we report on results from a transient BCL6 overexpression which lead us to believe that AID mRNA receives input from at least one alternate pathway in addition to BCL6. We also performed these experiments on a family of apolipoprotein B mRNA editing enzyme, catalytic polypeptide-like (APOBEC) cytidine deaminases, that show they may be involved in this pathway downstream of AID. Taken together, our results suggest a potential pathway involving BCL6, AID, and APOBEC cytidine deaminases that lead to the C to T transition that produces T790M, thereby conferring resistance to EGFR TKIs in mutant-EGFR NSCLC. They also provide potential new targets for treatment should further study confirm our results. / 2021-10-07T00:00:00Z

Small cell variant of medullary thyroid carcinoma is an extremely rare histologic entity with a paucity of data. As such, there is a lack of clinical experience regarding this disease. In this case, a 52-year-old patient with small cell variant medullary thyroid carcinoma was experiencing intractable nausea, vomiting, and diarrhea. The initial workup was extensive yet unrevealing. He was refractory to all treatments. On further laboratory analysis, the calcitonin was substantially high and the thyroid stimulating hormone level was mildly elevated. This case is presented to highlight a possible treatment for this rare cancer through thyroxine suppression therapy. This case is presented due to the lack of literature available on small cell medullary thyroid carcinoma and also to discuss a possible direct relationship between thyroid stimulating hormone and calcitonin levels in this disease population.

Prostate cancer is among the most common malignancies in males in the United States and adenocarcinoma accounts for 95% of all malignancies of prostate. Rarely prostate cancer can also present as small cell carcinoma. Pure small cell carcinoma is rare at time of initial diagnosis (<2%) however neuroendocrine differentiation into small cell carcinoma may emerge in men who have had previous treatment with ADT for prostate adenocarcinoma. These tumors, sometimes called treatment-related neuroendocrine prostate cancers or aggressive-variant prostate cancers, are increasingly recognized in the castration-resistant phases of disease progression. They account for less than 1% of all prostate cancers. A 73-year-old otherwise male had routine health screening in May 2018. Prostate specific antigen (PSA) level was elevated at 9.53 ng/mL. He had not had a screening PSA for at least two prior years but this was a significant change from prior levels. Patient was asymptomatic however the abnormal laboratory evaluation prompted consultation with Urology. Biopsy of prostate gland confirmed prostatic adenocarcinoma with Gleason's score of 5+ 4 = 9 with bilateral gland involvement. Imaging studies including CT scan of abdomen and pelvis, a bone scan and a PET scan showed no clear evidence of metastatic disease. Patient's clinical stage was determined to be IIIC with T2c N0 M0 disease. Patient began treatment with androgen deprivation therapy and received definitive radiation treatment with external bean radiation therapy from July to September 2018. PSA was 0.08 ng/ml at the end of radiation treatment. Patient did well for about 15 months, after which he had multiple hospital admissions for dyspnea, fluid retention and lower extremity edema. He was also found to have refractory hypokalemia. Patient underwent MRI brain which revealed numerous small enhancing calvarial and skull base lesions consistent with bony metastasis in the skull. Patient also underwent PET/CT scan which showed numerous thoracic spine bony lesions, numerous to count bony metastasis throughout the lumbar spine and pelvis, as well as multiple hepatic lesions. Patient underwent biopsy of right hepatic lobe lesion and pathology was consistent with small cell carcinoma with positive neuroendocrine markers including CD56, synaptophysin and TTF-1. Interestingly patient’s PSA was only 0.09ng/dL. Given refractory hypokalemia, paraneoplastic syndrome was suspected and further work-up was initiated. Serum cortisol levels were elevated at 119.6 mcg/dL (3.7-19.4) and ACTH level was 333 pg/mL (7.2 - 63.3). Aldosterone level was <1 ng/dL (0 - 30.0). Patient was diagnosed with paraneoplastic Cushing syndrome. Given aggressive nature of this small cell transformation, patient was started on treatment with systemic chemotherapy with Carboplatin/Etoposide during the hospital stay, with stabilization of potassium levels. Prostate small cell carcinoma poses a challenge for diagnosis and treatment. In contrast to adenocarcinoma of the prostate, serum prostate-specific antigen (PSA) is not predictive of disease severity, nor is it a useful tumor marker for monitoring progression or surveillance. Patients with prostate small cell cancer presents with more diverse symptoms than any other prostate cancer since it tends to metastasize early. Also paraneoplastic syndromes are more common in prostate small cell cancers as well.