Analyzing historical trends in breast cancer biomarker expression: a feasibility study (1947-2009)

Feasibility of analyzing DNA copy number variation in breast cancer tumor specimens from 1950 to 2010: how old is too old?

PURPOSE

The purpose of the study was to assess the feasibility of quantifying long-term trends in breast tumor DNA copy number variation (CNV) profiles.

METHODS

We evaluated CNV profiles in formalin-fixed paraffin-embedded (FFPE) tumor specimens from 30 randomly selected Kaiser Permanente Northern California health plan women members diagnosed with breast cancer from 1950 to 2010. Assays were conducted for five cases per decade who had available tumor blocks and pathology reports.

RESULTS

As compared to the tumors from the 1970s to 2000s, the older tumors dating back to the 1950s and 1960s were much more likely to (1) fail quality control, and (2) have fewer CNV events (average 23 and 31 vs. 58 to 69), fewer CNV genes (average 5.1 and 3.7k vs. 8.1 to 10.3k), shorter CNV length (average 2,440 and 3,300k vs. 5,740 to 9,280k), fewer high frequency Del genes (37 and 25% vs. 54 to 76%), and fewer high frequency high_Amp genes (20% vs. 56 to 73%). On average, assay interpretation took an extra 60 min/specimen for cases from the 1960s versus 20 min/specimen for the most recent tumors.

CONCLUSIONS

Assays conducted in the mid-2010s for CNVs may be feasible for FFPE tumor specimens dating back to the 1980s, but less feasible for older specimens.

Strong androgen receptor expression can aid in distinguishing GATA3+ metastases

GATA3 is a transcription factor used clinically as a marker of breast or urothelial differentiation. A marker is yet needed to distinguish this in the case of the GATA3-positive tumor of unknown origin. We tested classical markers of breast differentiation and hormonal signaling to see which correlated strongest with GATA3 expression in breast cancer and thus which could help correctly identify breast origin in the case of the GATA3-positive tumor of unknown origin. GATA3, estrogen receptor, progesterone receptor, androgen receptor (AR), HER2, GCDFP15, and mammaglobin expression was intercorrelated in a histologically diverse 259-case breast cancer tissue microarray. We show herein a uniquely high level of correlation between GATA3 and AR expression (r=0.61; 95% confidence interval 0.52-0.68) that was strongest among lobular carcinomas (r=1; 95% confidence interval 0.73-1) and stronger than any other correlation studied. Separate AR staining of 10 metastatic GATA3+ carcinomas of urothelial origin and 13 metastatic GATA3+ carcinomas of breast origin showed that strong AR staining (>60% of tumor cells) has a sensitivity of 54% and a specificity of 100% for correctly distinguishing GATA3+ carcinoma of mammary origin from urothelial origin in the metastatic setting. Androgen receptor expression is strongly correlated with GATA3 in breast cancer, particularly in tumors with lobular morphology. Strong AR expression (>60% of tumor cells) is an excellent test to rule out urothelial carcinoma in the GATA3+ metastatic setting (specificity 100%) and will effectively identify breast origin in approximately 50% of cases.

Tumor Specimen Biobanks: Data Gaps for Analyzing Health Inequities-the Case of Breast Cancer

Biobanks are increasingly recognized to be vital for analyzing tumor properties, treatment options, and clinical prognosis, yet few data exist on whether they are equipped to enable research on cancer inequities, that is, unfair and unnecessary social group differences in health. We conducted a systematic search of global biobanks, identified 46 that have breast tumor tissue and share data externally with academic researchers, and e-mailed and called to obtain data on the sociodemographic, socioeconomic, and geospatial data included, plus time span encompassed. Among the 32 biobank respondents, 91% housed specimens solely from the Global North, only 31% obtained socioeconomic data, 63% included racial/ethnic data (of which 55% lacked socioeconomic data), 44% included limited geographic data, and 55% had specimens dating back at most to 2000. To enable research to address cancer inequities, including trends over time, biobanks will need to address the data gaps documented by our study.

Feasibility of collecting tumor samples of breast cancer patients diagnosed up to 50 years ago in the Child Health and Development Studies

Environmental exposures during pregnancy may increase breast cancer risk for mothers and female offspring. Tumor tissue assays may provide insight regarding the mechanisms. This study assessed the feasibility of obtaining tumor samples and pathology reports from mothers (F0) who were enrolled in the Child Health and Development Studies during pregnancy from 1959 to 1967 and their daughters (F1) who developed breast cancer over more than 50 years of follow-up. Breast cancer cases were identified through linkage to the California Cancer Registry and self-report. Written consent was obtained from 116 F0 and 95 F1 breast cancer survivors to access their pathology reports and tumor blocks. Of those contacted, 62% consented, 13% refused and 24% did not respond. We obtained tissue samples for 57% and pathology reports for 75%, and if diagnosis was made ⩽10 years we obtained tissue samples and pathology reports for 91% and 79%, respectively. Obtaining pathology reports and tumor tissues of two generations is feasible and will support investigation of the relationship between early-life exposures and molecular tumor markers. However, we found that more recent diagnosis increased the accessibility of tumor tissue. We recommend that cohorts request consent for obtaining future tumor tissues at study enrollment and implement real-time tissue collection to enhance success of collecting tumor samples and data.