Unstaged Diffuse Large B Cell Lymphoma in the United States: Predictors and Patient Outcomes

Background: Treatment and prognosis of diffuse large B cell lymphoma (DLBCL) depends on the stage of lymphoma. We conducted this study to examine unstaged DLBCL in the United States.

Methods and methodology: We used Surveillance Epidemiology and End Result (SEER) 18 registries to select patients with DLBCL diagnosed during January 2000 to December 2012. We used LRD Summary stage 2000 was used to determine stage of the disease - localized, regional, distant or unstaged. We used Logistic regression to investigate factors associated with unstaged DLBCL. We used Cox Proportional Hazard model to compare survival outcomes.

Results: Among 67765 patients, 3194 (4.71%) were unstaged. Age (60+years), "Others" and Caucasian races, single or single/divorced/widow marital status, metropolitan residence, median household income> $50,000, lymph node as the primary site and cased with other primaries before diagnosis of DLBCL were the factors associated with unstaged cases (Table 1). The 5- year relative survival rate for unstaged patients was inferior to those with localized and regional disease, and superior to those with distant disease (HRs of 0.58, 0.66 and 1.24 for localized, regional and distant respectively when compared to unstaged cases). 

Conclusion: In this large population-based study, 4.71% patients with DLBCL had unstaged disease. Patients with unstaged DLBC had significantly inferior survival rates compared to patients with localized and regional stage.

Table 1: Factors associated with unstaged DLBCL cases:

Parameters	Unadjusted OR ( 95% CI)	P value	Adjusted OR ( 95% CI)	P value
Age ( 60+ Vs. <60 years)	1.478 (1.363 – 1.602)	<0.001	1.458 (1.335 – 1.592)	<0.001
Sex (Female Vs. Male)	1.063 (0.990 – 1.141)	0.093	0.983 (0.911 – 1.059)	0.646
Race
Caucasians	Reference		Reference
African American	0.804 (0.691 – 0.935)	0.005	0.835 (0.715 – 0.974)	0.022
Others	1.109 (0.976 – 1.261)	0.112	1.257 (1.104 – 1.431)	0.001
Marital Status
Married	Reference		Reference
Single	1.026 (0.927 – 1.135)	0.662	1.208 (1.086 – 1.345)	0.001
Single/divorced/widow	1.249 (1.152 – 1.355)	<0.001	1.185 (1.087 – 1.291)	<0.001
Rural/Urban
Rural	Reference		Reference
Urban	0.878 (0.651 – 1.183)	0.393	0.896 (0.661 – 1.214)	0.479
Metropolitan	0.882 (0.667 – 1.165)	0.882	1.028 (0.767 – 1.379)	0.852
Median annual household income
Upto 25,000	Reference		Reference
>25,000-50,000	01.009 (0.753 – 1.354)	0.951	0.927 (0.675 – 1.271)	0.636
>50,000	0.758 (0.563 – 1.021)	0.068	0.673 (0.486 – 0.933)	0.017
Sequence (Not first or only primary vs. first or only primary)	1.261 (1.156 – 1.377)	<0.001	1.219 (1.115 – 1.334)	<0.001
Site of primary
Lymph nodes	Reference		Reference
Extra-lymphatic	0.760 (0.704 – 0.821)	<0.001	0.748 (0.693 – 0.808)	<0.001
Unknown primary	6.295 (4.569 – 8.672)	<0.001	6.727 (4.865 – 9.300)	<0.001