PRIMARY OBJECTIVES:
I. To determine, as measured by the 3-year progression-free survival (PFS) rate and patterns of failure, whether dose and volume of irradiation can be safely reduced to 30.6 Gy whole ventricular-field irradiation (WVI) plus 23.4 Gy primary site boost instead of 36 Gy craniospinal irradiation (CSI) plus primary site boost in the subgroup of children and young adults (ages 3 to =\< 21 years) with localized nongerminomatous germ cell tumor (NGGCT) who have a magnetic resonance imaging (MRI) and tumor marker criteria (cerebrospinal fluid \[CSF\] and serum) for confirmed complete response (CR) or partial response (PR) to induction chemotherapy and negative serum and cerebrospinal fluid (CSF) tumor markers OR in patients who have less than a PR after induction chemotherapy with negative tumor markers who undergo a second-look surgery and are found to have only mature teratoma, residual scar or fibrosis and fit the definition of CR/PR after second-look surgery.
II. To determine, as measured by the 3-year PFS rate and patterns of failure, whether simplified chemotherapy followed by dose-reduced radiation therapy is effective for treating children and young adults (ages 3 to =\< 21 years) with localized primary central nervous system (CNS) germinoma who present with serum and/or CSF human chorionic gonadotropin-beta (hCGbeta) =\< 50 mIU/mL.
III. To prospectively evaluate and longitudinally model the cognitive, social, and behavioral functioning of children and young adults who are treated with reduced radiation dose and volume of irradiation in Stratum 1 (NGGCT) and with dose-reduced radiation therapy in Stratum 2 (germinoma) using the ALTE07C1 protocol.
SECONDARY OBJECTIVES:
I. To estimate the PFS and overall survival (OS) distributions of patients with NGGCT treated with 30.6 Gy WVI and involved-field radiation therapy (IFR) focal boost to 54 Gy.
II. To estimate the PFS and OS distributions of localized germinoma patients who present with a) serum and/or CSF hCGbeta =\< 50 mIU/mL and b) serum and/or CSF hCGbeta \> 50 mIU/mL and =\< 100 mIU/mL.
OUTLINE:
STRATUM I (NGGCT): Patients receive induction therapy comprising carboplatin intravenously (IV) over 15-60 minutes on day 1 and etoposide IV over 60-120 minutes on days 1-3 of courses 1, 3, and 5. Patients also receive ifosfamide IV over 60 minutes and etoposide over 60-120 minutes on days 1-5 of courses 2, 4, and 6. Treatment repeats every 21 days for 6 courses in the absence of disease progression or unacceptable toxicity. Patients achieving CR or PR undergo 3-dimensional conformal radiation therapy (3DRT) or intensity modulated radiation therapy (IMRT) once daily (QD) 5 days a week for 6 weeks. Patients with normalization of markers who fail to achieve CR or PR are strongly recommended to undergo second-look surgery. Patients who achieve CR or PR after second-look surgery undergo 3DRT or IMRT QD 5 days a week for 6 weeks.
STRATUM II (GERMINOMA): Patients receive induction therapy comprising carboplatin IV over 15-60 minutes on day 1 and etoposide IV over 60-120 minutes on days 1-3. Treatment repeats every 21 days for 4 courses in the absence of disease progression or unacceptable toxicity. Patients with CR or continued CR (CCR) undergo 3DRT or IMRT QD 5 days a week for 4 weeks. Patients with normalization of markers who fail to achieve CR or PR are strongly recommended to undergo second-look surgery. Patients found to have fibrosis, scar, mature teratoma, or non-viable tumor undergo 3DRT or IMRT QD 5 days a week for 4 weeks. Patients with stable disease (SD) or PR with \> 0.5 cm (suprasellar) or \> 1 cm (pineal) but =\< 1.5 cm residual disease do not undergo second-look surgery and undergo 3DRT or IMRT QD 5 days a week for 4 weeks.
After completion of study treatment, patients are followed up at 3, 6, and 9 months, every 4 months for 24 months, 30 months, 36 months, and then annually for up to 60 months.
Inclusion Criteria:
* Patients must be newly diagnosed with localized primary CNS NGGCT (Stratum 1) or localized primary CNS germinoma (Stratum 2); germ cell tumors located in the suprasellar, pineal, bifocal (pineal + suprasellar) and ventricles are eligible; tumors present in the above mentioned locations and with unifocal parenchymal extension are eligible
* Stratum 1(NGGCT): Patients must have one of the following criteria:
* Patients with serum and/or CSF hCGbeta \> 100 mIU/mL or any elevation of serum and/or CSF alpha-fetoprotein (AFP) \> 10 ng/mL or greater than the institutional normal are eligible, irrespective of biopsy results
* Patients with any of the following elements on biopsy/resection are eligible, irrespective of serum and/or CSF hCGbeta and AFP levels: endodermal sinus tumor (yolk sac), embryonal carcinoma, choriocarcinoma, malignant/immature teratoma, and mixed GCT with malignant GCT elements
* Stratum 2 (Germinoma): Patients must have both serum and CSF markers obtained (unless obtaining CSF is medically contraindicated) and must have one of the following criteria to be eligible:
* Patients with institutional normal AFP (or =\< 10 ng/mL if no institutional normal exists) in both serum and CSF (unless medically contraindicated) AND hCGbeta 5 to =\< 50 mIU/mL in serum and/or CSF (unless medically contraindicated) (only 1 is required to be elevated) are eligible; no histologic confirmation required
* Patients with bifocal (pineal + suprasellar) involvement or pineal lesion with diabetes insipidus (D1) AND hCGbeta =\< 100 mIU/mL in serum and/or CSF AND institutional normal AFP (or =\< 10 ng/mL if no institutional normal exists) in both serum and CSF (unless medically contraindicated) are eligible; no histologic confirmation required
* Patients with histologically confirmed germinoma or germinoma mixed with mature teratoma and hCGbeta =\< 100 mIU/mL in serum and/or CSF and institutional normal AFP (or =\< 10 ng/mL if no institutional normal exists) in both serum and CSF (unless medically contraindicated) are eligible
* All patients must have a cranial MRI with and without gadolinium at diagnosis/prior to enrollment; if surgical resection is performed, patients must have pre-operative and post-operative cranial MRI with and without gadolinium; the post-operative brain MRI should be obtained within 72 hours of surgery; if patient has a biopsy only, post-operative cranial MRI is recommended but not required; all patients must have a spine MRI with gadolinium obtained at diagnosis/prior to enrollment; Note: if the spine study is performed for the first time after surgical resection or biopsy, it is recommended to be obtained with and without gadolinium
* Lumbar CSF must be obtained prior to study enrollment unless medically contraindicated; if a patient undergoes surgery and lumbar CSF cannot be obtained at this time, then it should be performed at least 10 days following surgery before study enrollment; false positive cytology can occur within 10 days of surgery; Note: patients with positive CSF cytology obtained prior to 10 days after surgery may have cytology repeated to determine eligibility
* Patients must have CSF tumor markers obtained prior to enrollment unless medically contraindicated; ventricular CSF obtained at the time of CSF diversion procedure (if performed) is acceptable for tumor markers but lumbar CSF is preferred; in case CSF diversion and biopsy/surgery are combined, CSF tumor markers should be collected first
* Patients must be enrolled on ALTE07C1 prior to enrollment on ACNS1123; patients must be enrolled within 31 days of definitive diagnostic surgery (day 0) or clinical diagnosis
* Peripheral absolute neutrophil count (ANC) \>= 1,000/uL
* Platelet count \>= 100,000/uL (transfusion independent)
* Hemoglobin \>= 8.0 g/dL (may receive red blood cell \[RBC\] transfusions)
* Creatinine clearance or radioisotope glomular filtration rate (GFR) \>= 70 mL/min/1.73 m\^2 OR serum creatinine based on age/gender as follows:
* 0.8 mg/dL (2 to \< 6 years of age)
* 1.0 mg/dL (6 to \< 10 years of age)
* 1.2 mg/dL (10 to \< 13 years of age)
* 1.5 mg/dL (male) and 1.4 mg/dL (female) (13 to \< 16 years of age)
* 1.7 mg/dL (male) and 1.4 mg/dL (female) (\>= 16 years of age)
* Total bilirubin =\< 1.5 times upper limit of normal (ULN) for age
* Serum glutamic oxaloacetic transaminase (SGOT) (aspartate aminotransferase \[AST\]) and serum glutamate pyruvate transaminase (SGPT) (alanine aminotransferase \[ALT\]) \< 2.5 times ULN
* Patients with seizure disorder may be enrolled if well controlled
* Patients must not be in status, coma, or assisted ventilation prior to study enrollment
Exclusion Criteria:
* Patients with mature teratoma or completely resected immature teratoma with normal tumor markers are not eligible
* Patients with tumors located outside the ventricles (basal ganglia, thalamus) are not eligible
* Patients with metastatic disease by cranial or spinal MRI evaluation or CSF cytology (unless medically contraindicated) are not eligible
* Patients must not have received any prior tumor-directed therapy other than surgical intervention and corticosteroids
* Female patients who are pregnant are ineligible
* Lactating females are not eligible unless they have agreed not to breastfeed their infants
* Female patients of childbearing potential are not eligible unless a negative pregnancy test result has been obtained
* Sexually active patients of reproductive potential are not eligible unless they have agreed to use an effective contraceptive method for the duration of their study participation
* All patients and/or their parents or legal guardians must sign a written informed consent
* All institutional, Food and Drug Administration (FDA), and National Cancer Institute (NCI) requirements for human studies must be met
