Radiation Medicine Commons^™

Investigating The Necessity Of Adaptive Radiotherapy In Tomotherapy Of Head And Neck Cancer Patients, Ali Chaparian, Mahsa Kianinia, Mahnaz Roayaei, Nadia Najafizade, Abolfazl Kanani, Leili Mahani, Hamidreza Nourzadeh

Department of Radiation Oncology Faculty Papers

BACKGROUND: Anatomical variations that occur during radiation therapy in head and neck cancer (HNC) patients can lead to significant dosimetric changes. The purpose of this study is to evaluate dosimetric and volume changes in key anatomical structures for different treatment sites in HNC patients, and to determine the percentage of patients who need adaptive radiotherapy (ART) per treatment site.

METHODS: A total of 1,740 megavoltage computed tomography (MVCT) images from 58 HNC patients treated with helical tomotherapy (HT) were exported to the PreciseART™ (Accuray) software. Volume changes in the planning target volume (PTV) and the organs at risk (OARs) in …

Desmoplastic Small Round Cell Tumor: An Update Of Current Management Practices, Ahmed Gawash, Alexa Simonetti, Brandon J Goodwin, Alissa Brotman O'Neill

Rowan-Virtua School of Osteopathic Medicine Departmental Research

BACKGROUND: Desmoplastic small round cell tumor (DSRCT) poses a diagnostic challenge, initiating with imaging techniques like ultrasound, CT, MRI, and PET scans, with CT being the primary choice for abdominal tumor visualization. Despite advances, the absence of a standardized staging system complicates the diagnostic process.

METHODS: A comprehensive literature review and search strategy, encompassing databases like PubMed and Cochrane was performed.

RESULTS: Systemic chemotherapy, notably the P6 regimen, is the cornerstone of DSRCT treatment, while other options, including CDK4/6 inhibitors, antibody-drug conjugates, and anlotinib present varying efficacy. A novel chemotherapeutic agent, ONC-201, exhibits promise, inhibiting tumor growth in preclinical models. …

Chemoradiation Treatment With Or Without Concurrent Tumor-Treating Fields (Ttfields) Therapy In Newly Diagnosed Glioblastoma (Gbm) Patients In China, Liping Liang, Lingchao Chen, Chunxia Ni, Wenyin Shi, Zhirui Zhou, Shu Chen, Wenjia Zhu, Jiabing Liu, Xianxin Qiu, Wanzun Lin, Junyan Zhang, Zhiyong Qin, Yang Wang

Department of Radiation Oncology Faculty Papers

BACKGROUND: Tumor-treating fields (TTFields) therapy and radiotherapy may have synergistic anti-glioma effect based on preclinical studies. The combination of chemoradiation therapy (CRT) with TTFields therapy has noticeably attracted clinicians' attention. This study aimed to provide insights into the clinical outcomes of patients with newly diagnosed glioblastoma who received either concurrent CRT and TTFields therapy or adjuvant TTFields therapy following CRT. The findings were based on a cohort of patients who were treated at Huashan Hospital (Shanghai, China).

METHODS: This retrospective study analyzed ndGBM patients' clinical outcomes who were treated at Huashan Hospital and received TTFields therapy. Patients were categorized into …

Atypical Presentation Of Non-Small Cell Lung Carcinoma With Metastasis To Breast Tissue, Tylar P. Seckman, Diane Krutzler-Berry, Mohamed Ashal, Waqas Mahmud, Krista L. Denning, Logan M. Lawrence

Marshall Journal of Medicine

Malignant neoplasms of the lung commonly metastasize to lymph nodes, bone, brain, and liver via hematogenous and lymphatic routes. Much less commonly, metastasis occurs in the breast. Secondary metastatic disease of the breast is very rare, with a reported incidence ranging from 0.4-1.3%­­—with primary lung cancer being one of the most anomalous sources. This case details non-small cell lung cancer metastasis to the breast with proven primary contralateral lung origination. This atypical finding prompts medical professionals to consider these malignant cells' immunologic, histologic, and pathologic makeup to understand further and treat the neoplasm.

Durable Local Control With Hypofractionated Radiation Therapy For Unresectable Or Metastatic Melanoma, Sydney A Keatts, Aya F Salem, David M Swanson, Ahsan S Farooqi, Andrew J Bishop, Rodabe N Amaria, Jennifer L Mcquade, Isabella C Glitza Oliva, Adi Diab, Roi Weiser, Sarah B Fisher, Ryan P Goepfert, Merrick I Ross, B Ashleigh Guadagnolo, Devarati Mitra

Faculty, Staff and Student Publications

BACKGROUND AND PURPOSE: As patients with advanced melanoma live longer in the context of systemic therapy advancements, better strategies for durable control of bulky tumors are needed. In this study, we evaluated if dose-escalated hypofractionated radiation therapy (HFRT) can provide durable local control and improve tumor-associated symptoms in patients with unresectable or bulky metastatic melanoma for whom stereotactic ablative radiotherapy (RT) approaches are not feasible due to tumor size or location.

MATERIALS AND METHODS: We retrospectively reviewed 49 patients with unresectable or bulky metastatic melanoma who were treated to a total of 53 tumor targets with 12-17 fractions HFRT at …

Comparative Plan Analysis: Helical Tomotherapy Vs. Linac Vmat For Lower Extremity Sarcomas, Marie E. Dibona

Masters Projects

Abstract

Introduction

Soft tissue sarcomas (STS) affect about 13,500 people annually in the United States, and those in the lower extremities present unique challenges in radiation therapy due to the wide variability in tumor sizes, sometimes exceeding 30cm. Traditional treatment involves C-Arm linear accelerators using Volumetric Modulated Radiation Therapy (VMAT), which provides precise targeting while sparing nearby organs. Helical Tomotherapy (HT) is another option, delivering radiation in a helical pattern with a binary MLC for a uniform dose distribution. However, no studies have compared VMAT and HT for lower extremity sarcomas of different sizes. This study aims to compare these …

Assessing Breast Disease With Deep Learning Model Using Bimodal Bi-View Ultrasound Images And Clinical Information, Fengping Liang, Yihua Song, Xiaoping Huang, Tong Ren, Qiao Ji, Yanan Guo, Xiang Li, Yajuan Sui, Xiaohui Xie, Lanqing Han, Yuanqing Li, Yong Ren, Zuofeng Xu

Faculty, Staff and Students Publications

Breast cancer is the second leading cause of carcinoma-linked death in women. We developed a multi-modal deep-learning model (BreNet) to differentiate breast cancer from benign lesions. BreNet was constructed and trained on 10,108 images from one center and tested on 3,762 images from two centers in three steps. The diagnostic ability of BreNet was first compared with that of six radiologists; a BreNet-aided scheme was constructed to improve the diagnostic ability of the radiologists; and the diagnosis of real-world radiologists' scheme was then compared with the BreNet-aided scheme. The diagnostic performance of BreNet was superior to that of the radiologists …

Early Outcomes Of Mr-Guided Sbrt For Patients With Recurrent Pancreatic Adenocarcinoma, Spencer Poiset, Sophia Shah, Louis Cappelli, Rani Anné, Karen Mooney, Maria Werner-Wasik, Talya Laufer, James Posey, Daniel Lin, Atrayee Mallick, Harish Lavu, Babar Bashir, Charles Yeo, Adam Mueller

Kimmel Cancer Center Faculty Papers

BACKGROUND: Local treatment options for locally recurrent pancreatic adenocarcinoma (LR-PAC) are limited, with median survival time (MST) of 9-13 months (mos) following recurrence. MRI-guided stereotactic body radiation therapy (MRgSBRT) provides the ability to dose escalate while sparing normal tissue. Here we report on the early outcomes of MRgSBRT for LR-PAC.

METHODS: Patients with prior resection of pancreatic adenocarcinoma with local recurrence treated with MRgSBRT at a single tertiary referral center from 5-2021 to 2-2023 were identified from our prospective database. MRgSBRT was delivered to 40-50 Gy in 4-5 fractions with target and OAR delineation per institutional standards. Endpoints included local …

Resection And Reconstruction Of Ewing Sarcoma Of The Cuboid Utilizing Vascularized Fibular Autograft: A Case Report, Brandon Cunha, Alexandre Arkader

Rowan-Virtua Research Day

Ewing Sarcoma (EWS) rarely presents in the bones of the foot, and particularly in the cuboid, making it an exceedingly rare occurrence. We present the case of a 7-year-old female diagnosed with EWS of the right cuboid, detailing the management and outcomes of this rare presentation. The patient, now almost 5 years post-initial local control, exhibits restored foot function, a normalized gait, and no evidence of disease recurrence. This case underscores the potential for preserving lower extremity function and improving postoperative quality of life in rare presentations of EWS through innovative reconstruction strategies.

Acute Pain Prediction In Oral Cavity And Oropharyngeal Cancer Patients Receiving Radiation Therapy, Vivian Salama

Dissertations and Theses (Open Access)

Oral-Cavity and oropharyngeal cancers (OC/OPC) are types of head and neck cancers that are increasing in incidence domestically. Radiation therapy (RT) is crucial in OC/OPC management. Pain is a common and challenging symptom for most patients during therapy, as nearly all patients undergoing locoregional RT in OC/OPC require analgesia for acute iatrogenic pain. Moreover, about 45% of long-term survivors report chronic pain, with more than 10% exhibiting severe chronic pain. Pain control is challenging due to the multifactorial clinical, molecular, and cellular etiology of cancer/therapy pain, as well as variation in pain assessment and the non-uniform management of pain between …

Real World Clinical Experience Using Daily Intelligence-Assisted Online Adaptive Radiotherapy For Head And Neck Cancer, Philip Blumenfeld, Eduard Arbit, Robert Den, Ayman Salhab, Tal Falick Michaeli, Marc Wygoda, Yair Hillman, Raphael Pfeffer, Marcel Fang, Yael Misrati, Noam Weizman, Jon Feldman, Aron Popovtzer

Department of Radiation Oncology Faculty Papers

Background

Adaptive radiation therapy (ART) offers a dynamic approach to address structural and spatial changes that occur during radiotherapy (RT) for locally advanced head and neck cancers. The integration of daily ART with Cone-Beam CT (CBCT) imaging presents a solution to enhance the therapeutic ratio by addressing inter-fractional changes.

Methods

We evaluated the initial clinical experience of daily ART for patients with head and neck cancer using an online adaptive platform with intelligence-assisted workflows on daily CBCT. Treatment included auto-contour and structure deformation of Organs at Risk (OARs) and target structures, with adjustments by the treating physician. Two plans were …

Quality Assurance For Stereotactic Body Radiation Therapy For Gynecologic Malignancies, Samuel N Andersen, Mark D Bonnen, Michelle S Ludwig, Shraddha M Dalwadi

Faculty, Staff and Students Publications

The use of stereotactic body radiation therapy (SBRT) is not well studied or reported in the treatment of gynecologic malignancies, despite its success in the definitive management of other cancer sites. This report describes a rigorous quality assurance process for patients to undergo dose escalation to the pelvis via stereotactic photon beam irradiation. Patients who receive SBRT must be ineligible for conventional brachytherapy boost and undergo comprehensive informed consent. Fiducial placement, bowel prep, Foley catheter placement with standardized bladder filling, computerized tomography (CT) simulation with whole-body immobilization, magnetic resonance imaging (MRI)-assisted target delineation, planning aims based on the established brachytherapy …

Developing Radiosensitizers To Enhance Radiotherapy In Treating Gastroenteropancreatic Neuroendocrine Tumor, Zeta Chow

Theses and Dissertations--Clinical and Translational Science

Gastroenteropancreatic Neuroendocrine Tumor (GEP-NET) is a heterogeneous group of malignancies arising from multipotent neuroendocrine stem cells in the gastrointestinal tract. The incidence of GEP-NET continues to rise, possibly due to the advancement of imaging and biomarkers available for diagnosis. However, even though the majority of patients are diagnosed with low-grade and localized disease, a significant percentage of patients present with advanced-stage metastatic disease with poor prognosis in months to a few years. These advanced-stage GEP-NET patients can also present with a variety of debilitating symptoms that significantly impact their quality of life. The role of palliative-intent surgery is limited, and …

Conditional Risks Of Biochemical Failure And Prostate Cancer-Specific Death In Patients Undergoing External Beam Radiotherapy: A Secondary Analysis Of 2 Randomized Clinical Trials, Gregory S. Alexander, Rebecca F Krc, James W Assif, Kai Sun, Jason K Molitoris, Phuoc Tran, Zaker Rana, Søren M Bentzen, Mark V Mishra

Department of Radiation Oncology Faculty Papers

IMPORTANCE: As patients achieve years of survival after treatment for prostate cancer, the risk of biochemical failure (BF) or prostate cancer-specific death (PCSD) may evolve over time, with clinical relevance to both patients and clinicians.

OBJECTIVE: To determine conditional BF-free survival, PSCD, and overall survival estimates for patients with low- or intermediate-risk prostate cancer enrolled in the Radiation Therapy Oncology Group (RTOG) 0126 and RTOG 0415 clinical trials. A secondary objective was to determine whether prognostic factors at diagnosis remain relevant at later points in follow-up.

DESIGN, SETTING, AND PARTICIPANTS: A pooled secondary analysis of patients treated with external-beam radiotherapy …

Multiple Primary Lung Cancers: Treatment Outcomes After Stereotactic Body Radiotherapy (Sbrt), Gyujae Choi, George Chen, Weiyuan Mai, Albert Chen, Angela Zhu

Faculty, Staff and Students Publications

PURPOSE/OBJECTIVES: Patients with lung cancer sometimes present with multiple primary lung cancers (MPLCs), either simultaneously (synchronous) or after treatment of an initial lesion (metachronous). Although open surgery remains a treatment mainstay for patients with stage I-II non-small-cell lung cancer (NSCLC), stereotactic body radiation therapy (SBRT) is an acceptable alternative for patients who are medically unfit for or who refuse surgery. In this study, we retrospectively examine the outcome among patients with early-stage MPLCs treated at our institution with SBRT.

MATERIALS/METHODS: Patients at our institution receiving SBRT for MPLC between June 2011 and March 2020 were reviewed retrospectively. Prior to undergoing …

Multiparametric Magnetic Resonance Imaging Artificial Intelligence Pipeline For Oropharyngeal Cancer Radiotherapy Treatment Guidance, Kareem Wahid

Dissertations and Theses (Open Access)

Oropharyngeal cancer (OPC) is a widespread disease and one of the few domestic cancers that is rising in incidence. Radiographic images are crucial for assessment of OPC and aid in radiotherapy (RT) treatment. However, RT planning with conventional imaging approaches requires operator-dependent tumor segmentation, which is the primary source of treatment error. Further, OPC expresses differential tumor/node mid-RT response (rapid response) rates, resulting in significant differences between planned and delivered RT dose. Finally, clinical outcomes for OPC patients can also be variable, which warrants the investigation of prognostic models. Multiparametric MRI (mpMRI) techniques that incorporate simultaneous anatomical and functional information …

Radiation Therapy For Retroperitoneal Sarcomas: A Strass-Ful Situation, Ahsan S Farooqi, B Ashleigh Guadagnolo, Devarati Mitra, Andrew J Bishop

Faculty, Staff and Student Publications

Locoregional recurrence (LRR) is the predominant pattern of relapse and often the cause of death in patients with retroperitoneal sarcomas (RPS). As a result, reducing LRR is a critical objective for RPS patients. However, unlike soft tissue sarcomas (STS) of the superficial trunk and extremity where the benefits of radiation therapy (RT) are well-established, the role of RT in the retroperitoneum remains controversial. Historically, preoperative or postoperative RT, either alone or in combination with intraoperative radiation (IORT), was commonly justified for RPS based on extrapolation from the superficial trunk and extremity STS literature. However, long-awaited results were recently published from …

The Contribution Of Patient Reported Outcome Measures To Shared Decision-Making In Radiation Oncology At A Midwestern Comprehensive Cancer Center, Kellie Bodeker

Doctor of Philosophy in Translational Health Sciences Dissertations

Background. Chronic diseases, such as lung cancer, require a provider-patient relationship developed over time. This relationship fosters shared decision-making (SDM), a collaborative, dynamic information exchange and analysis between provider and patient regarding treatment and desired outcomes. Established benefits to SDM include an improved quality of life and decreased anxiety and depression. Despite established benefits, recent research suggests radiation oncologists are not engaging in SDM. A decision-aid tool utilizing patient reported outcome measures may increase SDM between radiation oncologists and patients with lung cancer. Patient-reported outcome measures, wherein the patient provides direct assessment of their health and quality of life, …

External Beam Radiation Therapy Carries Lower Risk Of Sexual Dysfunction As Compared To Radical Prostatectomy In Treatment Of Patients With Localized Prostate Cancer, Aamod S. Dekhne

Clinical Research in Practice: The Journal of Team Hippocrates

A clinical decision report appraising:

Donovan JL, Hamdy FC, Lane JA, et al. Patient-Reported Outcomes after Monitoring, Surgery, or Radiotherapy for Prostate Cancer. N Engl J Med. 2016;375(15):1425-1437. https://doi.org/10.1056/NEJMoa1606221

for a patient with localized prostate cancer and concerns regarding future sexual dysfunction.

Nuclear-Targeted Gold Nanoparticles Enhance The Effects Of Radiation Therapy With And Without Liposomal Delivery, Maureen Aliru

Dissertations and Theses (Open Access)

Less that 10% of pancreatic cancer patients are eligible for curative resection, and clinical trials evaluating chemoradiation in locally advanced patients with unresectable disease have been largely disappointing. New and creative therapeutic approaches are needed to address the unment need for treatment options. The objective of this thesis is to advance radiosensitization of treatment-resistant densely desmoplastic pancreatic cancer using nanoparticles to surmount biological barriers to effective particle distribution for DNA-targeting.

Clinical translation of radiosensitizing nanoparticles has stalled owing to technical challenges. Current strategies to use AuNPs for radiosensitization require large quantities of gold, kilovoltage x-rays, immediate irradiation after intravenous administration, …

Atrx Loss In Pediatric Glioma Results In Epigenetic Dysregulation Of G2/M Checkpoint Maintenance And Sensitivity To Atm Inhibition, Brendan Mullan, Tingting Qin, Ruby Siada, Carla Danussi, Jacqueline Brosnan-Cashman, Drew Pratt, Taylor Garcia, Viveka Nand Yadav, Xinyi Zhao, Meredith Morgan, Sriram Venneti, Alan Meeker, Alnawaz Rehemtulla, Pedro Lowenstein, Maria Castro, Carl Koschmann

Medical Student Research Symposium

ATRX is a histone chaperone protein recurrently mutated in pediatric glioma. The mechanism which mediates the proliferative advantage of ATRX loss in pediatric glioma remains unexplained. Recent data revealed a distinct pattern of DNA binding sites of the ATRX protein using ChIP-seq in mouse neuronal precursor cells (mNPCs). Using the ATRX peaks identified in p53^-/- mNPCs, we confirmed that ATRX binding sites were significantly enriched in gene promoters (p < 0.0001) and CpG islands (p < 0.0001) compared with random regions. Gene set enrichment (GSE) analysis identified that cell cycle and regulation of cell cycle were among the most significantly enriched gene sets (p=2.52e-16 and 1.61e-9, respectively). We found that ATRX loss resulted in dysfunction of G2/M checkpoint maintenance: (1) ATRX-deficient pediatric glioblastoma (GBM) cells exhibited a seven-fold increase in mitotic index at 16 hours after sub-lethal radiation, and (2) murine GBM cells with ATRX knockdown demonstrated impaired pChk1 signaling on western blot at multiple time points after radiation compared to controls (p=0.0187). Notably, the ATM signaling (pChk2) remained intact in those cells, suggesting a potential therapeutic target. ATRX-deficient mouse cells were uniquely sensitive to ATM inhibitors at 1 uM alongside 8 Gy radiation compared to controls with intact ATRX (AZD0156: p=0.0027 and AZD01390: p=0.0436). Mice intra-cranially implanted with ATRX-deficient GBM cells showed improved survival (n=10, p=0.0018) when treated with AZD0156 combined with radiation. Our findings suggest that ATRX loss in glioma results in unique sensitivity to ATM inhibition via epigenetic dysregulation of G2/M checkpoint maintenance.

Adjuvant Therapy In Adrenocortical Carcinoma: Reflections And Future Directions, Sara Bedrose, Marilyne Daher, Lina Altameemi, Mouhammed Amir Habra

Faculty, Staff and Students Publications

Adrenocortical carcinoma (ACC) is a rare and aggressive malignancy with high risk of recurrence despite macroscopically complete surgical resection. The main predictors of ACC recurrence include advanced disease stage, incomplete surgical resection, cortisol production, certain genetic alterations, and high proliferation rate (Ki-67 proliferation index). Mitotane has been the mainstay adjuvant therapy of ACC. However, the use of mitotane is based on retrospective and occasionally conflicting evidence. As mitotane levels can take a few months before reaching therapeutic levels, there is an emerging practice of combining platinum-based chemotherapy with mitotane in the adjuvant setting. Retrospective data indicate that radiotherapy is an …

Prediction Of Anal Cancer Recurrence After Chemoradiotherapy Using Quantitative Image Features Extracted From Serial (18)F-Fdg Pet/Ct, Michael Chuong

All Publications

No abstract provided.

Management Of Patients With Brain Metastases From Non-Small Cell Lung Cancer And Adverse Prognostic Features: Multi-National Radiation Treatment Recommendations Are Heterogeneous, Minesh Mehta

All Publications

No abstract provided.

Weighing The Risks And Benefits Of Radiation Exposure And Diagnostic X-Rays In Children, Leah Costello

Physician Assistant Scholarly Project Posters

The number of X-rays, specifically CT scans, performed on patients in the United States is increasing exponentially every year. Children are at most risk for long term damage from this increase in radiation exposure. This study explores how much risk children are being exposed to and how we can, as practitioners, make informed decisions about when or when not to order CT scans. The purpose of this paper is to provide practitioners the information needed to help patients decide if the long-term risks of cancer from medical radiation outweigh the potential benefit of diagnostic or therapeutic radiation. The review of …

The Relationship Between The Level Of Support Group Participation And Psychosocial Factors In Prostate Cancer Patients Treated With Proton Therapy, Carol A. L. Davis

Loma Linda University Electronic Theses, Dissertations & Projects

Background. The role of support groups for cancer patients is known to be beneficial in helping people adjust to the disease, and cope with the myriad of effects that cancer has on quality of life. Although many people express interest in attending such support groups, few attend regularly. It is unclear what characteristics distinguish those who use such services from those who do not, especially among proton therapy patients.

Objective. To examine demographic and psychosocial characteristics associated with the Brotherhood of the Balloon (BOB) prostate cancer support group membership, a unique treatment-focused group originating at Loma Linda University Medical Center …

Effects Of Liposome-Encapsulated Tnf-Alpha And Radiation Against Colon Cancer, Dong Won Kim

Loma Linda University Electronic Theses, Dissertations & Projects

Previous studies have shown that tumor necrosis factor-α (TNF-α) can augment the antitumor effects of radiation, inhibiting tumor progression to a greater extent than either modality alone. However, nonspecific toxicities associated with TNF-α have limited its use as an adjuvant. This limitation is potentially resolved with the encapsulation of TNF-α in sterically stabilized, PEGylated liposomes (STEALTH®). Thus, the overall hypothesis of the research was that the combination of radiation with STEALTH® liposome encapsulated TNF-α (SL-TNF-α) will have greater efficacy and fewer dose-limiting side effects in the LS174T human colorectal tumor xenograft model compared to the combination of free TNF-α and …

A Preclinical Model Of Ionizing Radiation And Tnf-Alpha Gene Therapy For Cancer, Jun Li

Loma Linda University Electronic Theses, Dissertations & Projects

Long term control of high-grade brain tumors is rarely achieved with current therapeutic regimens. This study sought to determine if pretreatment with plasmid DNA expressing Tumor Necrosis Factor-α (TNF-α) could enhance the effect of ionizing radiation in an aggressive, rapidly growing glioma tumor (C6) model. Plasmid DNA is an attractive vector system for delivery of foreign genes into eukaryotic cells due to its advantages including low immunogenicity in vivo, lesser toxicity and relatively low cost. We have constructed a plasmid-based mammalian expression vector (pGL1-TNF) to secrete human TNF-α from cancer cells. Plasmid DNA was successfully transfected into C6 cells …

Cell Mediated Immunity By Cytotoxicity Assay And The Effect Of Corynebacterium Parvum And Radiation On Mice Bearing Herpes-Induced Tumors, Robert B. Stagg

Loma Linda University Electronic Theses, Dissertations & Projects

Cell mediated immune (CMI) cytotoxic reactivity of Balb/c mice against H238 cells, a Herpes simplex virus (HSV) Type 2 - induced sarcoma, was measured by the ¹²⁵IUdR release assay. The Balb/c mouse response to the growing HSV-induced tumor, treated with radiation and , was measured by survival rate, tumor growth and immune cytotoxicity of spleen and peritoneal exudate cells (PEC) as determined by ¹²⁵IUdR release assay. Subcutaneous (s.c.) inoculation of 1 x 10⁶ H238 cells (high dose) produced progressive tumor growth while s.c. inoculation of 1 x 10⁴ H238 cells (low dose) produced no tumors. A …