Inclusion Criteria

DISEASE CHARACTERISTICS:

- Histologically or cytologically confirmed malignant neoplasm

- Not amenable to standard therapy or has failed existing first- and second-line
therapies

- Tumor positive for somatostatin receptors by OctreoScan within the past 4 weeks

- At least 1 measurable lesion

- Lesions that have been previously irradiated must demonstrate progression since
radiation

- At least 1 measurable somatostatin receptor-positive lesion that has not been
irradiated within the past 4 weeks AND has not had full craniospinal radiation
within the past 3 months

- Bone marrow with at least 40% cellularity OR at least 20% cellularity with one
million CD34+ stem cells/kg stored

- No diffuse bone marrow involvement by OctreoScan scintigraphy

PATIENT CHARACTERISTICS:

Age

- 2 to 25

Performance status

- COG 0-2 OR

- Karnofsky 60-100% OR

- Lansky 60-100%

Life expectancy

- 2-12 months

Hematopoietic

- See Disease Characteristics

- Absolute neutrophil count at least 1,000/mm^3

- Platelet count at least 100,000/mm^3

Hepatic

- Bilirubin less than 1.5 times normal

- AST and ALT less than 2.5 times upper limit of normal

Renal

- Creatinine no greater than 1 mg/dL (children less than 5 years of age)

- Creatinine less than 1.2 mg/dL (children 5 to 10 years of age)

- Creatinine less than 1.7 mg/dL (children over 10 years of age) AND

- Glomerular filtration rate at least 80 mL/min/m^2

Cardiovascular

- Shortening fraction at least 28% by echocardiogram

- Ejection fraction at least 50% by bi-plane method of echocardiogram

- No prior congestive heart failure unless ejection fraction at least 40%

- No unstable angina pectoris

- No cardiac arrhythmia

- No symptomatic congestive heart failure

Other

- No other concurrent malignancy

- No other significant uncontrolled medical, psychiatric, or surgical condition that
would preclude study compliance

- No antibodies to yttrium Y 90-DOTA-tyr3-octreotide or octreotide

- No prior allergic reactions to compounds of similar chemical or biologic composition
to yttrium Y 90-DOTA-tyr3-octreotide

- No ongoing or active infection

- Not pregnant or nursing

- Negative pregnancy test

- Fertile patients must use effective contraception during and for 6 months after study
participation

PRIOR CONCURRENT THERAPY:

Biologic therapy

- Not specified

Chemotherapy

- At least 4 weeks since prior chemotherapy (6 weeks for nitrosoureas or mitomycin)

Endocrine therapy

- More than 28 days since prior long-acting somatostatin analogues

- No concurrent somatostatin analogues 12 hours before or 12 hours after study drug
administration

- Concurrent hormonal therapy (other than somatostatin analogue) allowed provided
patient received hormonal therapy for at least 2 months and has stable disease or
progressive disease

Radiotherapy

- See Disease Characteristics

- At least 4 weeks since prior radiotherapy

- No prior radiotherapy to 25% or more of bone marrow

- No prior external beam radiotherapy to both kidneys (scatter doses of less than 500
cGy to a single kidney or radiation to less than 50% of a single kidney is allowed)

Surgery

- At least 4 weeks since prior surgery

Other

- Recovered from prior therapy

- At least 4 weeks since prior investigational drugs

- No other concurrent approved or investigational anti-neoplastic therapies except for
bisphosphonates

- No concurrent combination antiretroviral therapy for HIV-positive patients