Gamma camera scans and pretreatment tumor volumes as predictors of response and progression after Y-90 anti-CD20 radioimmunotherapy

Int J Radiat Oncol Biol Phys. 2005 Sep 1;63(1):194-201. doi: 10.1016/j.ijrobp.2005.01.017.


Purpose: To evaluate two potential approaches to predicting site-specific patterns of recurrence after yttrium-90 ibritumomab tiuxetan radioimmunotherapy (RIT) for CD20+ B-cell Non-Hodgkin's lymphoma. These predictive methods may be useful in evaluating the utility of local intensification of individual nodal or extranodal sites using external beam radiotherapy.

Methods and materials: Records and images were evaluated for 20 patients previously treated with yttrium-90 ibritumomab RIT. Intensity of isotope uptake on the pretreatment two-dimensional antibody scans and maximal extent of tumor deposits found on computed tomography images of each anatomic site were correlated with response and subsequent patterns of recurrence or progression.

Results: Our data failed to suggest a significant correlation between the site-by-site two-dimensional image intensity on the pre-RIT scan and the likelihood of response at those sites. In contrast, an analysis of pretreatment target volumes did correlate significantly with progression. A collective analysis of disease sites from all 20 patients found that 83% (10/12) sites of "bulky" (maximal diameter > or = 5 cm) disease displayed evidence of progression vs. 28% (26/93) of "nonbulky" disease sites containing gross disease but no area measuring >5 cm (p < 0.001). All patients with at least one site of bulky disease had initial disease progression occur at a bulky site, with a bulky site being the sole first site of progression in approximately 50%. In patients with only nonbulky disease sites, approximately one third progressed initially at an entirely new site of disease.

Conclusion: We conclude that we can use tumor bulk to establish a statistical hierarchy of likely tumor progression sites and use this pattern to direct the use of additional external beam radiotherapy to augment treatment.

Publication types

  • Evaluation Study

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Antibodies, Monoclonal / therapeutic use*
  • Antigens, CD20 / immunology*
  • Disease Progression
  • Female
  • Gamma Cameras
  • Humans
  • Indium Radioisotopes
  • Lymphoma, B-Cell / diagnostic imaging
  • Lymphoma, B-Cell / pathology
  • Lymphoma, B-Cell / radiotherapy*
  • Male
  • Middle Aged
  • Prognosis
  • Radioimmunotherapy / methods*
  • Radionuclide Imaging
  • Recurrence
  • Treatment Outcome
  • Yttrium Radioisotopes / therapeutic use*


  • Antibodies, Monoclonal
  • Antigens, CD20
  • Indium Radioisotopes
  • Yttrium Radioisotopes
  • ibritumomab tiuxetan