involvement of bone marrow ( bm ) has been reported in 10 - 30% of cases of diffuse large b - cell lymphoma ( dlbcl ) . due to its prognostic and therapeutic implications , bm involvement in patients with dlbcl is of critical importance . in general , patients with bm involvement are known to have a more aggressive clinical course and advanced disease than patients without bm involvement . thus , bm involvement showed an association with significantly shorter survivals in patients with dlbcl . rituximab is a chimeric monoclonal antibody against the protein cd20 , which is found primarily on the surface of malignant b - cells . the addition of rituximab to cyclophosphamide , vincristine , adriamycin , and prednisolone ( chop ) has led to a notable improvement in the response rate and survival outcomes for patients with dlbcl . several recent studies have demonstrated that inclusion of rituximab in combination chemotherapy can result in a significantly improved therapeutic effect on dlbcl with bm involvement . some studies have also reported that rituximab could relieve the negative impact of bm involvement . nevertheless , it is still uncertain whether rituximab plus chop ( rchop ) can alter the clinical outcome of patients with bm involvement in dlbcl . accordingly , we evaluated the prognosis of dlbcl patients with bm involvement who received rchop . we conducted a retrospective review of the medical records of 567 patients with newly diagnosed dlbcl who received rchop at six centers between november 2001 and march 2010 . all of the patients were evaluated using standard laboratory tests , computed tomography ( ct ) scans , and a unilateral bm aspirate and biopsy at the time of diagnosis . all of the bm biopsies were analyzed by a pathologist and a hematologist using standard immunohistochemistry , along with a visual assessment . additional information was also abstracted , including age , sex , performance status , presence of b symptoms ( fever , night sweats , and weight loss ) , presence of bulky disease ( defined as tumor size>10 cm ) , presence of extranodal disease , presence of bm involvement , international prognostic index ( ipi ) scoring system , serum lactate dehydrogenase ( ldh ) , hemoglobin ( hb ) , white blood cells ( wbc ) , and platelets ( plt ) . an elevated ldh was defined as greater than 480 u / l according to the upper normal limit . all of the patients were treated with six cycles of rchop , while patients with a bulky disease received six cycles of rchop with radiotherapy . overall survival ( os ) was defined as the time from diagnosis to death from any cause . event - free survival ( efs ) was defined as the time from diagnosis to failure or death from any cause . os and efs were analyzed using the kaplan - meier test , and each group was compared using a log - rank test . we conducted a retrospective review of the medical records of 567 patients with newly diagnosed dlbcl who received rchop at six centers between november 2001 and march 2010 . all of the patients were evaluated using standard laboratory tests , computed tomography ( ct ) scans , and a unilateral bm aspirate and biopsy at the time of diagnosis . all of the bm biopsies were analyzed by a pathologist and a hematologist using standard immunohistochemistry , along with a visual assessment . additional information was also abstracted , including age , sex , performance status , presence of b symptoms ( fever , night sweats , and weight loss ) , presence of bulky disease ( defined as tumor size>10 cm ) , presence of extranodal disease , presence of bm involvement , international prognostic index ( ipi ) scoring system , serum lactate dehydrogenase ( ldh ) , hemoglobin ( hb ) , white blood cells ( wbc ) , and platelets ( plt ) . an elevated ldh was defined as greater than 480 u / l according to the upper normal limit . all of the patients were treated with six cycles of rchop , while patients with a bulky disease received six cycles of rchop with radiotherapy . the descriptive statistics are reported as the proportion and median . overall survival ( os ) event - free survival ( efs ) was defined as the time from diagnosis to failure or death from any cause . os and efs were analyzed using the kaplan - meier test , and each group was compared using a log - rank test . the median age of patients was 61.0 years ( range , 16 to 89 years ) and 56.3% were male ; 230 ( 40.6% ) patients had stage iii and iv at diagnosis , and 107 patients ( 40.6% ) were categorized as high or high - intermediate risk according to their ipi . the overall incidence of bm involvement was 8.5% . in patients with normal ldh and a normal complete blood count ( cbc ) , 1.8% had bm involvement . among these 48 patients with bm involvement , the median age was 60.0 years ( range , 17 to 78 years ) and 64.6% were male . the median cbc values were hb 11.1 g / dl , wbc 6.510/l , and plt 15210/l . twenty six patients remain alive , while 20 patients relapsed and 26 patients later died . with a median follow - up duration of 33.2 months ( range , 0.1 to 80.7 months ) , among patients who were alive at the last follow - up , the five - year os and efs rate was 74.6% and 65.4% , respectively . as shown in fig . 1 , the five - year os and efs rate in patients without bm involvement ( 76.3% and 67.5% , p<0.001 ) was statistically higher than that in patients with bm involvement ( 44.3% and 40.1% , p<0.001 ) . in multivariate analysis , among total patients , bm involvement showed a significant association with os and efs ( table 2 ) . in univariate and multivariate analyses , even among stage iv patients , bm involvement group showed a significant association with worse efs ( table 3 , fig . the median age of patients was 61.0 years ( range , 16 to 89 years ) and 56.3% were male ; 230 ( 40.6% ) patients had stage iii and iv at diagnosis , and 107 patients ( 40.6% ) were categorized as high or high - intermediate risk according to their ipi . the overall incidence of bm involvement was 8.5% . in patients with normal ldh and a normal complete blood count ( cbc ) , 1.8% had bm involvement . among these 48 patients with bm involvement , the median age was 60.0 years ( range , 17 to 78 years ) and 64.6% were male . the median cbc values were hb 11.1 g / dl , wbc 6.510/l , and plt 15210/l . twenty six patients remain alive , while 20 patients relapsed and 26 patients later died . with a median follow - up duration of 33.2 months ( range , 0.1 to 80.7 months ) , among patients who were alive at the last follow - up , the five - year os and efs rate was 74.6% and 65.4% , respectively . 1 , the five - year os and efs rate in patients without bm involvement ( 76.3% and 67.5% , p<0.001 ) was statistically higher than that in patients with bm involvement ( 44.3% and 40.1% , p<0.001 ) . in multivariate analysis , among total patients , bm involvement showed a significant association with os and efs ( table 2 ) . in univariate and multivariate analyses , even among stage iv patients , bm involvement group showed a significant association with worse efs ( table 3 , fig . the result of the current study demonstrates that patients with bm involvement have a worse prognosis than patients without bm involvement , even after receiving rituximab - containing therapy . the poor prognosis of patients with bm involvement has already been described in a number of studies . conlan et al .   reported that bm involvement predicted a short survival . in a separate study , however , the significant improvement in treatment outcomes observed following the introduction of rituximab has altered risk assessment in dlbcl . in fact , the ipi is a powerful tool for predicting the clinical outcome in patients with aggressive non - hodgkin lymphoma . however , only a few studies have used the ipi score for prediction and examination of the prognosis in dlbcl with bm involvement . recently reported an association of concordant bm involvement with poor prognosis , which was independent of the ipi . likewise , in the current study , the distribution of ipi scores for the patients also varied from 2 to 5 . this study pursued an in - depth report on the 48 patients with bm involvement . although bm involvement itself is a poor risk , the common features associated with primary bm dlbcl include an advanced lymphoma stage with relative old age and poor performance . most of our patients were also found to have poor clinical factors , including advanced age , poor performance status , elevated ldh level , and b symptoms at diagnosis . these findings are consistent with those of a previous report on the features of bm involvement . addition of rituximab to chop has led to a notable improvement in the response rate and survival outcomes for patients with dlbcl . recent studies have also demonstrated that the inclusion of rituximab in combination chemotherapy has a significantly improved therapeutic effect on dlbcl with bm involvement . although the precise relationship between rituximab and bm involvement is not well understood , rituximab appears to efficiently eradicate neoplastic lymphoid cells in bm . in general , rituximab is a therapeutic antibody that binds to a particular protein , the cd20 antigen , on the surface of normal and malignant b - cells . it then recruits the body 's natural defences to attack and kill the marked b - cells . stem cells in bm lack the cd20 antigen , allowing for regeneration of healthy b - cells after treatment and return to normal levels within several months . according to abe et al . , rituximab treatment for relapsed cd20 positive acute lymphoblastic leukemia resulted in complete prevention of regrowth of bone tumors . some studies have also reported that lymphoma patients who presented with only bm disease at diagnosis were treated successfully with rituximab and combination chemotherapy . more specifically , rituximab therapy in the case of autoimmune disease shows selective depletion of pathogenic autoreactive b - cell clones in bm , as demonstrated by molecular analysis . therefore , these observations indicated that bm involvement may not have a significant impact on the prognosis of patients who receive rchop . however , in the current study , a significant difference in five - year os and efs was observed between patients with and without bm involvement who received rchop . in addition , after adjusting for other factors , multivariate analysis according to os and efs also showed that bm involvement had a negative influence on survival . in univariate and multivariate analyses , even among stage iv patients this finding suggests that treatment approach to dlbcl with bm involvement should be considered separately from those for dlbcl with normal bm . some data support the use of intensive multiagent chemotherapy in eradication of neoplastic cells in bm . in addition , more intensive regimens have been used in lymphoblastic lymphoma , which typically presents as a widely disseminated disease with frequent bm involvement . our data showed that bm involvement at diagnosis had a negative impact on survival in patients with dlbcl who received rchop . these results suggest that bm involvement is still a negative prognostic factor of dlbcl patients in the era of rituximab . prognostic subgroup analysis should be evaluated and validated for patients with bm involvement , and a more suitable treatment compatible with bm involvement will be further investigated in patients with bm involvement .
purposewe investigated the clinical outcome of bone marrow ( bm ) involvement in patients with diffuse large b - cell lymphoma ( dlbcl ) who received rituximab - based therapy.materials and methodsa total of 567 consecutive patients with newly diagnosed dlbcl treated with rituximab - chop ( rchop ) between november 2001 and march 2010 were included in the current study . 
 all of the patients underwent a bm study at the initial staging and the clinical characteristics and prognosis of these patients with or without bm involvement were analyzed retrospectively.resultsthe total cohort included 567 patients . 
 the overall incidence of bm involvement was 8.5% . with a median follow - up duration of 33.2 months ( range , 0.1 to 80.7 months ) for patients who were alive at the last follow - up , 
 the five - year overall survival ( os ) and event - free survival ( efs ) rate in patients without bm involvement ( 76.3% and 67.5% , p<0.001 ) was statistically higher than that in patients with bm involvement ( 44.3% and 40.1% , p<0.001 ) . 
 in multivariate analysis , among total patients , bm involvement showed a significant association with os and efs . in univariate and multivariate analyses , even among stage iv patients , a significant association with worse efs was observed in the bm involvement group.conclusionbm involvement at diagnosis affected the survival of patients with dlbcl who received rchop . 
 although use of rchop can result in significant improvement of the therapeutic effect of dlbcl , bm involvement is still a negative prognostic factor of dlbcl patients in the era of rituximab .