Intensity-Modulated Radiation Therapy to the Pelvis With or Without Chemotherapy in Treating Patients With Endometrial Cancer or Cervical Cancer That Has Been Removed By Surgery

DISEASE CHARACTERISTICS:

* Must have undergone a hysterectomy (total abdominal, vaginal, radical, or laparoscopic-assisted vaginal) within 7 weeks prior to study entry

  * Patients with endometrial cancer must have also undergone a bilateral salpingo-oophorectomy
* Histologically confirmed diagnosis of 1 of the following:

  * Endometrial cancer meeting 1 of the following criteria:

    * Stage IB grade 3, IC grade 1-3, IIA, or IIB disease requiring postoperative pelvic radiotherapy
    * Unstaged (no lymph node dissection or sampling) stage IB grade 2 disease
    * Stage IIIC with all of the following:

      * Pelvic lymph node positive only
      * Para-aortic nodes sampled negative
      * Not receiving chemotherapy
  * Cervical cancer meeting 1 of the following criteria:

    * Post-radical hysterectomy and requires postoperative pelvic radiotherapy due to any of the following:

      * Positive pelvic nodes (negative para-aortic nodes)
      * Microscopic parametrial involvement and negative margins
      * Disease qualified by Sedlis criteria must have 2 of the following risk factors:

        * 1/3 or more stromal invasion
        * Lymph-vascular space invasion
        * Large clinical tumor diameter (≥ 4 cm)
    * Post-simple hysterectomy with negative margins and negative nodes by CT scan, MRI, or positron emission tomography-CT scan
* No requirement for extended-field radiotherapy beyond the pelvis
* No histologically confirmed papillary serous, clear cell, or neuroendocrine (either large or small cell) disease, endometrial stromal sarcoma, leiomyosarcoma, or malignant müllerian mixed tumor
* No evidence of metastatic disease outside of the pelvis
* No microscopic involvement of the resection margin (\< 3 mm)

PATIENT CHARACTERISTICS:

* Zubrod performance status 0-2
* WBC (white blood cell count) ≥ 4,000/mm³ (cervical cancer patients only)
* Absolute neutrophil count ≥ 1,800/mm³ (cervical cancer patients only)
* Platelet count ≥ 100,000/mm³ (cervical cancer patients only)
* Hemoglobin ≥ 8.0 g/dL (transfusion allowed)
* Serum creatinine ≤ 2.0 mg/dL (cervical cancer patients only)
* Creatinine clearance ≥ 50 mL/min (cervical cancer patients only)
* AST (aspartate aminotransferase) ≤ 2 times upper limit of normal
* Bilirubin ≤ 2 times upper limit of normal
* Patients must not exceed the weight and size limits of the treatment table or CT scanner

  * No mental status changes or bladder control problems that would preclude study compliance with bladder-filling instructions
* No active inflammatory bowel disease
* No severe, active, concurrent illness, defined as any of the following:

  * Unstable angina and/or congestive heart failure requiring hospitalization within the past 6 months
  * Transmural myocardial infarction within the past 6 months
  * Acute bacterial or fungal infection requiring IV antibiotics
  * Chronic obstructive pulmonary disease exacerbation or other respiratory illness requiring hospitalization or precluding study therapy
  * Hepatic insufficiency resulting in clinical jaundice and/or coagulation defects
  * AIDS
* No history of allergy to cisplatin (cervical cancer patients)
* No prior invasive malignancy (except nonmelanoma skin cancer) unless disease-free for ≥ 3 years

PRIOR CONCURRENT THERAPY:

* See Disease Characteristics
* No prior radiotherapy to the pelvis that would result in overlap of radiotherapy fields
* No prior platinum-based chemotherapy (cervical cancer patients)
* No concurrent prophylactic growth factors (e.g., filgrastim \[G-CSF\], sargramostim \[GM-CSF\], or pegfilgrastim)
* No concurrent prophylactic thrombopoietic agents
* No concurrent amifostine or other protective agents