Abstract P3-07-10: Rising incidence of primary breast lymphoma: SEER 1973-2011
Authors: Thomas Alexandra , Schroeder Mary C , McDowell Bradley D , Link Brian K 
Published: May 2015

Abstract
Background: Primary breast lymphomas (PBL) are rare and most commonly of B-cell origin: diffuse large B-cell or extranodal marginal zone lymphomas. Recent reports have described breast-implant associated anaplastic large T- cell lymphoma. Other lymphomas arising from the breast have also been described less frequently, with plastic surgery. We hypothesized that the overall incidence of primary breast lymphomas may also be increasing. This study reports the incidence of PBL as first malignancy as recorded in Surveillance, Epidemiology and End Results Program (SEER) from 1973-2011. Mortality and first local therapy are also reported.
Methods: Using the SEER 9 Research Data, we conducted a retrospective cohort analysis of women diagnosed with microscopically confirmed, first primary malignant lymphoma arising in the breast from 1973 through 2011. Cases were excluded if they were reported to the registry by a nursing home or diagnosed by autopsy or death certificate. PBLs were categorized by the SEER lymphoid malignancy recode variable. We evaluated trends in age-adjusted incidence rates, first local therapy, and age-adjusted all-cause and cause-specific mortality across time.
Results: The overall incidence of PBL has increased more than 3 fold, from 0.07/100,000 in 1973-82 to 0.23/100,000 in 2003-11 (p&lt; 0.001) (Table 1).
Table 1: Primary Breast Lymphoma- Incidence (age-adjusted rate, per 100,000 women)1973-19821983-19921993-20022003-2011p valueAll0.10.10.20.2&lt;0.001Age&lt;500.00.00.10.05&lt;0.00150+0.20.40.60.7&lt;0.001LymphomaHodgkins0.00.0020.0030.002&lt;0.001NHL-B-cell0.040.10.20.2&lt;0.001DLBCL0.030.10.10.10.001Follicular0.0050.020.030.040.062Marginal Zone0.00.00.030.1&lt;0.001NHL-T-cell0.00.0010.0040.01&lt;0.001
By age, the greatest incidence increase was for women 50 and older (0.02/100,000 in 1973-82 to 0.68/100,000 in 2003-11, p&lt;0.001). Both B-cell marginal zone lymphoma and T-cell lymphoma have had steep increases in incidence from 1983-1992 to 2003-2011 (0/100,000 to 0.06/100,000, p&lt;0.001 and 0.001/100,000 to 0.008/100,000, p&lt;0.001, respectively). The incidence of DLBC and follicular lymphomas arising in the breast rose from 1973-1992 and subsequently stabilized. Age-adjusted, all-cause mortality has dropped significantly since 1992, as has cause-specific mortality (Table 2).
Table 2: Primary Breast Lymphoma-Mortality and Initial Local TherapyAge-adjusted, 5-year Mortality (% deceased)1973-19821983-19921993-20022003-2011p valueAll-cause51%54%33%22%&lt;0.001Cause-specific43%43%25%15%&lt;0.001Initial Local therapy (% received)Both26%26%23%12%0.274Radiation only8%11%18%31%&lt;0.001Surgery only59%47%34%16%&lt;0.001None4%14%21%40%&lt;0.001
For the entire cohort, no local therapy and radiation therapy, as initial local treatment, has increased over time. Surgery alone has decreased substantially.
Conclusions: Primary breast lymphoma remains a rare diagnosis; however the incidence has risen markedly over the last four decades, with B-cell marginal zone and T-cell lymphomas increasing significantly in the most recent time period. Further research is required to better understand the factors contributing to these trends. Survival gains over time suggest either that lymphoma treatments have improved or that the excess cases are treatment responsive or non-survival-threatening.
Citation Format: Alexandra Thomas, Mary C Schroeder, Bradley D McDowell, Brian K Link. Rising incidence of primary breast lymphoma: SEER 1973-2011 [abstract]. In: Proceedings of the Thirty-Seventh Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2014 Dec 9-13; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2015;75(9 Suppl):Abstract nr P3-07-10.