Diffuse Large B-Cell Lymphoma (DLBCL) is the most common cause (30%) of Non Hodgkin's Lymphoma (NHL). DLBCL may be associated with B symptoms: fever, weight loss and drenching sweat. In 40% of cases the disease is extra-nodal and most commonly affects the stomach/gastro-intestinal tract but may also involve other sites - include the CNS.

DLBCL commonly affects the middle aged and the elderly and the average age is 64 yrs. It has a slightly higher incidence in men and 60 % of people are diagnosed at stage III/IV.

Treatment and prognosis depends on Ann Arbor staging (Stage I, II, III, and IV). Current standard treatment for DLBCL is CHOP-Rituximab given every three weeks for six to eight cycles. Survival of DLBCL is based on the International Prognostic Index IPI) and is decreased by presence of five parameters each with a point index of 1: age > 60 yrs, elevated LDH, performance status greater or equal to 2, Advanced Stage (III/IV), and number of involved extra nodal disease. A Revised International Prognostic Index predicts outcomes as follows: IPI score of 0 as Very good (94% overall survival, 94% progression free survival), IPI score of 1 or 2 as Good (79% overall survival, 80% progression free survival), and IPI score of greater or equal to 3 as poor (55% overall survival, 53% progression free survival).

There is evidence that the presence of elevated CA-125 appears to be a useful predictor of aggressive histology and bulky disease and its presence at the time of diagnosis has also been associated with a decreased 5-year survival. Data indicate that serum CA 125 is a useful tumor marker in NHL patients that may improve staging and CA 125 levels reflect the patient's response to the invasive potential of the tumor, giving a measurement of its infiltrative activity.

Recommended follow up is with CT scans at months 6, 12, 18, 24, 30 or 36 months and then yearly until five years after attainment of a complete remission. No more imaging is performed after five years unless an abnormality suggests the possibility of relapse or the patient requests it.

Following completion of treatment, some patients may have residual masses on CT scanning containing only fibroticc tissue or non-viable tumor and may be mistakenly considered as not having achieved complete remission.

PET scanning or combined PET/CT scanning is suggested to resolve most cases. Whenever PET-positive disease at the completion of treatment is identified a tissue biopsy or further evaluation is required, as some of these patients remain in prolonged remission. PET or PET/CT imaging is not used routinely in the longitudinal follow-up of asymptomatic patients after response assessment.