RATIONALE: Radiolabeled monoclonal antibodies, such as iodine I 131 tositumomab and yttrium Y 90 ibritumomab tiuxetan, can find cancer cells and carry cancer-killing substances to them without harming normal cells. This may be an effective treatment for non-Hodgkin's lymphoma.

PURPOSE: This clinical trial is studying the side effects, best dose, and how well iodine I 131 tositumomab or yttrium Y 90 ibritumomab tiuxetan works in treating patients with non-Hodgkin's lymphoma.

OBJECTIVES:

Primary

• Determine the relationship between estimated absorbed dose and tumor response using different dosimetric methodologies in patients with non-Hodgkin's lymphoma treated with iodine I 131 tositumomab or yttrium Y 90 ibritumomab tiuxetan.
• Determine the relationship between estimated absorbed dose and normal organ toxicity using different dosimetric methodologies in these patients.

Secondary

• Assess the difference in the dose-response relationship between dosimetric methodologies in these patients.
• Assess the influence of prior therapy on the dose-response relationship for hematologic toxicity in these patients.

OUTLINE: Patients are stratified according to planned radioimmunotherapy treatment (iodine I 131 tositumomab vs yttrium Y 90 ibritumomab tiuxetan).

• Stratum 1: Patients receive dosimetric rituximab IV followed by indium In 111 (^111In) ibritumomab tiuxetan IV over 10 minutes on day 1. Patients undergo positron emission tomography (PET)/CT scans and single-photon emission computed tomography (SPECT)/CT scans between 2-24, 48-72, and 90-120 hours after ^111In ibritumomab tiuxetan administration. Patients who have acceptable biodistribution receive therapeutic rituximab IV followed by yttrium Y 90 ibritumomab tiuxetan IV over 10 minutes between days 7-9.
• Stratum 2: Patients receive dosimetric tositumomab IV over 60 minutes followed by iodine I 131 (^131I) tositumomab IV over 20 minutes on day 0. Patients undergo PET/CT scans and SPECT/CT scans on days 0; 2, 3 or 4; and 6 or 7. Patients who have acceptable biodistribution receive therapeutic tositumomab IV over 60 minutes followed by ^131I tositumomab IV over 20 minutes on approximately day 7.

In both strata, blood is collected at baseline to measure FLT-3 levels. All patients also undergo a baseline PET/CT scan.

After completion of study treatment, patients are followed every 3 months for 1 year and then every 6 months thereafter.

PROJECTED ACCRUAL: A total of 88 patients will be accrued for this study.

DISEASE CHARACTERISTICS:

• Diagnosis of non-Hodgkin's lymphoma
• Measurable disease by CT scan or nuclear medicine imaging
• Eligible, by standard of care criteria, for iodine I 131 tositumomab or yttrium Y 90 ibritumomab tiuxetan treatment

PATIENT CHARACTERISTICS:

• No other malignancy within the past 3 years except basal cell carcinoma or squamous cell carcinoma of the skin or in situ carcinoma of the cervix
• Not pregnant or nursing
• Fertile patients must use effective contraception
• No alcoholism or drug abuse within the past 2 years
• No severe emotional, behavioral, or psychiatric problems that would limit study compliance

PRIOR CONCURRENT THERAPY:

• No concurrent participation in another investigational drug study

All patients treated for NHL by rituximab or zevalin

Patients being treated for lymphoma using I-131-labeled antibody were imaged and tumor dosimetry was performed using conventional and patient-specific dosimetry. Tumors could not be detected on imaging for 2 of the 9 enrolled patients.

Adverse event data was not collected since this was a data collection study tacked on to routine patient treatment