Testing Whether the Use of Brain Scans Alone Instead of Brain Scans plus Preventive Brain Radiation Affects Lifespan in Participants with Small Cell Lung Cancer

Inclusion Criteria

• Participant must have pathologically confirmed small-cell lung cancer (SCLC) (which may include cytological or histological confirmation)
• Participant must have an MRI of the brain performed within 28 days prior to registration documenting no evidence of brain metastases or leptomeningeal disease. Participant also must not have a history of brain metastases or leptomeningeal disease
• Immunotherapy concurrent with and/or adjuvant to first-line therapy is allowed at the discretion of the treating physician. Participants with limited-stage (LS)-SCLC must have completed platinum-based chemotherapy and either definitive thoracic radiotherapy (including stereotactic body radiation therapy [SBRT] for early-stage disease who do not undergo surgery) or definitive surgical resection; thoracic radiation in addition to definitive surgical resection is allowed at the discretion of the treating physician, but is not required. Participants with extensive-stage (ES)-SCLC must have completed the platinum-based chemotherapy component of their treatment course
• All adverse events from prior treatment must have resolved to =< grade 2 (Common Terminology Criteria for Adverse Events [CTCAE] version 5.0) prior to randomization
• Participant must have had a response to first-line therapy and no evidence of progression in opinion of the treating investigator. Systemic imaging (CT including the chest plus or minus abdomen/pelvis or PET/CT) must be performed within 42 days prior to randomization
• No more than 16 weeks may have elapsed between day 1 of the last cycle of chemotherapy and randomization
• Participant must not have received prior radiotherapy to the brain or whole brain radiotherapy. Participants who have undergone prior stereotactic radiosurgery for benign tumors or conditions (e.g., acoustic neuroma, grade I meningioma, trigeminal neuralgia) may be considered on a case-by-case basis
• Participant must be >= 18 years of age
• Participant must have Zubrod performance status of 0-2
• Participant must not have a contraindication to MR imaging, such as implanted metal devices or foreign bodies
• Participant must not have a contraindication to gadolinium contrast administration during MR imaging, such as allergy or insufficient renal function
• Participant must not have other metastatic malignancies requiring current active treatment
• Participant must not have any severe active comorbidities, defined as follows: * Unstable angina and/or congestive heart failure requiring hospitalization within 3 months prior to randomization * Transmural myocardial infarction within 3 months prior to randomization * Acute bacterial or fungal infection requiring intravenous antibiotics at the time of randomization * Acute severe exacerbation of chronic obstructive pulmonary disease or other acute respiratory illness precluding study therapy at the time of randomization * Severe hepatic disease defined as a diagnosis of Child-Pugh class B or C hepatic disease * Human immunodeficiency virus (HIV) positive with CD4 count < 200 cells/microliter. Note that participants who are HIV positive are eligible, provided they are under treatment with highly active antiretroviral therapy (HAART) and have a CD4 count >= 200 cells/microliter within 16 weeks prior to randomization. Note also that HIV testing is not required for eligibility for this protocol
• Participant must not be pregnant because of fetal risks from radiation exposure. Men must have agreed to use an effective contraceptive method during PCI and for six months after completing PCI. Women of reproductive potential must have agreed to use an effective contraceptive method during PCI. A woman is considered to be of "reproductive potential" if she has had menses at any time in the preceding 12 consecutive months. In addition to routine contraceptive methods, "effective contraception" also includes heterosexual celibacy and surgery intended to prevent pregnancy (or with a side-effect of pregnancy prevention) defined as a hysterectomy, bilateral oophorectomy or bilateral tubal ligation. However, if at any point a previously celibate participant chooses to become heterosexually active during the time period for use of contraceptive measures outlined in the protocol, he/she is responsible for beginning contraceptive measures
• Participants registered by sites located in the United States who speak English must agree to complete cognitive function testing at the protocol specified timepoints. Participants registered by sites located in Canada who speak English or French must agree to complete the cognitive function testing at the protocol specified timepoints.
• Participants must be offered the opportunity to have specimens submitted for banking * NOTE: The specimens for banking collection is limited to participants at US sites only
• Participants registered by sites located in the United States and Canada who can complete the Quality of Life Instruments in English, Spanish, or French, must agree to participate in the questionnaires at the protocol specified timepoints. NOTE: Participants enrolled prior to the release and implementation of Revision #3 are not eligible for the Quality of Life study.
• Participants must be informed of the investigational nature of this study and must sign and give written informed consent in accordance with institutional and federal guidelines
• As a part of the Oncology Patient Enrollment Network (OPEN) randomization process the treating institution’s identity is provided in order to ensure that the current (within 365 days) date of institutional review board approval for this study has been entered in the system