Risk of myelodysplastic syndrome and acute myeloid leukemia post radiation treatment for breast cancer: a population-based study

Second primary cancer risks according to race and ethnicity among U.S. breast cancer survivors

Breast cancer survivors have an increased risk of developing second primary cancers, yet risks by race and ethnicity have not been comprehensively described. We evaluated second primary cancer risks among 717,335 women diagnosed with first primary breast cancer (aged 20-84 years and survived ≥1-year) in the SEER registries using standardized incidence ratios (SIRs; observed/expected). SIRs were estimated by race and ethnicity compared with the racial- and ethnic-matched general population, and further stratified by clinical characteristics of the index breast cancer. Poisson regression was used to test for heterogeneity by race and ethnicity. SIRs for second primary cancer differed by race and ethnicity with the highest risks observed among non-Hispanic/Latina Asian American, Native Hawaiian, or other Pacific Islander (AANHPI), non-Hispanic/Latina Black (Black), and Hispanic/Latina (Latina) survivors and attenuated risk among non-Hispanic/Latina White (White) survivors (SIRAANHPI = 1.49, 95% CI = 1.44-1.54; SIRBlack = 1.41, 95% CI = 1.37-1.45; SIRLatina = 1.45, 95% CI = 1.41-1.49; SIRWhite = 1.09, 95% CI = 1.08-1.10; p-heterogeneity<.001). SIRs were particularly elevated among AANHPI, Black, and Latina survivors diagnosed with an index breast cancer before age 50 (SIRs range = 1.88-2.19) or with estrogen receptor-negative tumors (SIRs range = 1.60-1.94). Heterogeneity by race and ethnicity was observed for 16/27 site-specific second cancers (all p-heterogeneity's < .05) with markedly elevated risks among AANHPI, Black, and Latina survivors for acute myeloid and acute non-lymphocytic leukemia (SIRs range = 2.68-3.15) and cancers of the contralateral breast (SIRs range = 2.60-3.01) and salivary gland (SIRs range = 2.03-3.96). We observed striking racial and ethnic differences in second cancer risk among breast cancer survivors. Additional research is needed to inform targeted approaches for early detection strategies and treatment to reduce these racial and ethnic disparities.

Radiation and leukaemia: Which leukaemias and what doses?

The cause(s) of most cases of leukaemia is unknown. Save for several rare inherited disorders the most convincingly-identified causes of leukaemia are exposures to ionizing radiations, to some chemicals and to some anti-cancer drugs. Data implicating ionizing radiations as a cause of leukaemias come from several sources including persons exposed to the atomic bomb explosions in Japan, persons receiving radiation therapy for cancer and other disorders, persons occupationally exposed to radiation such as radiologists and nuclear facility workers, cigarette smokers, and others. Although ionizing radiations can be a cause of almost all types of leukaemias, some are especially sensitive to induction such as acute and chronic myeloid leukaemias (AML and CML) and acute lymphoblastic leukaemia (ALL). Whether chronic lymphocytic leukaemia can be caused by radiation exposure is controversial. The mechanism(s) by which ionizing radiations cause leukaemia differs for different leukaemia types. I discuss these issues and close with a hypothesis which might explain why haematopoietic stem cells are localized to the bone marrow.

Maximizing Breast Cancer Therapy with Awareness of Potential Treatment-Related Blood Disorders

In this review we summarize the impact of the various modalities of breast cancer therapy coupled with intrinsic patient factors on incidence of subsequent treatment-induced myelodysplasia and acute myelogenous leukemia (t-MDS/AML). It is clear that risk is increased for patients treated with radiation and chemotherapy at younger ages. Radiation is associated with modest risk, whereas chemotherapy, particularly the combination of an alkylating agent and an anthracycline, carries higher risk and radiation and chemotherapy combined increase the risk markedly. Recently, treatment with granulocyte colony-stimulating factor (G-CSF), but not pegylated G-CSF, has been identified as a factor associated with increased t-MDS/AML risk. Two newly identified associations may link homologous DNA repair gene deficiency and poly (ADP-ribose) polymerase inhibitor treatment to increased t-MDS/AML risk. When predisposing factors, such as young age, are combined with an increasing number of potentially leukemogenic treatments that may not confer large risk singly, the risk of t-MDS/AML appears to increase. Patient and treatment factors combine to form a biological cascade that can trigger a myelodysplastic event. Patients with breast cancer are often exposed to many of these risk factors in the course of their treatment, and triple-negative patients, who are often younger and/or BRCA positive, are often exposed to all of them. It is important going forward to identify effective therapies without these adverse associated effects and choose existing therapies that minimize the risk of t-MDS/AML without sacrificing therapeutic gain. IMPLICATIONS FOR PRACTICE: Breast cancer is far more curable than in the past but requires multimodality treatment. Great care must be taken to use the least leukemogenic treatment programs that do not sacrifice efficacy. Elimination of radiation and anthracycline/alkylating agent regimens will be helpful where possible, particularly in younger patients and possibly those with homologous repair deficiency (HRD). Use of colony-stimulating factors should be limited to those who truly require them for safe chemotherapy administration. Further study of a possible leukemogenic association with HRD and the various forms of colony-stimulating factors is badly needed.

Risk of myeloid neoplasms after radiotherapy among older women with localized breast cancer: A population-based study

Background

There are inconsistent and limited data regarding the risk of myeloid neoplasms (MN) among breast cancer survivors who received radiotherapy (RT) in the absence of chemotherapy. Concern about subsequent MN might influence the decision to use adjuvant RT for women with localized disease. As patients with therapy-related MN have generally poor outcomes, the presumption of subsequent MN being therapy-related could affect treatment recommendations.

Methods

We used the Surveillance, Epidemiology, and End Results (SEER)–Medicare linked database to study older women with in-situ or stage 1–3 breast cancer diagnosed 2001–2009 who received surgery. Chemotherapy and RT were ascertained using Medicare claims, and new MN diagnoses were captured using both SEER registry and Medicare claims. We excluded women who received chemotherapy for initial treatment, and censored at receipt of subsequent chemotherapy. Competing-risk survival analysis was used to assess the association between RT and risk of subsequent MN adjusting for relevant characteristics.

Results

Median follow-up for 60,426 eligible patients was 68 months (interquartile range, 46 to 92 months), with 47.6% receiving RT. In total, 316 patients (0.52%) were diagnosed with MN; the cumulative incidence per 10,000 person-years was 10.6 vs 9.0 among RT-treated vs non-RT-treated women, respectively (p = .004); the increased risk of subsequent MN persisted in the adjusted analysis (hazard ratio = 1.36, 95% confidence interval: 1.03–1.80). The results were consistent in multiple sensitivity analyses.

Conclusions

Our data suggest that RT is associated with a significant risk of subsequent MN among older breast cancer survivors, though the absolute risk increase is very small. These findings suggest the benefits of RT outweigh the risks of development of subsequent MN.

Myelodysplastic Syndromes and Acute Myeloid Leukemia After Radiotherapy for Prostate Cancer: A Population-Based Study

BACKGROUND

To understand the impact of radiotherapy on the development of myelodysplastic syndromes (MDS) and acute myeloid leukemia (AML) among elderly prostate cancer patients.

METHODS

We performed a retrospective cohort study of elderly prostate cancer patients diagnosed during 1999-2011 by using the National Cancer Institute's Surveillance, Epidemiology and End Results-Medicare linked database. Competing risk analyses adjusting for patient characteristics were conducted to assess the impact of radiotherapy on the development of subsequent MDS/AML, compared with surgery.

RESULTS

Of 32,112 prostate cancer patients, 14,672 underwent radiotherapy, and 17,440 received surgery only. The median follow-up was 4.68 years. A total of 157 (0.47%) prostate cancer patients developed subsequent MDS or AML, and the median time to develop MDS/AML was 3.30 (range: 0.16-9.48) years. Compared with prostate cancer patients who received surgery only, patients who underwent radiotherapy had a significantly increased risk of developing MDS/AML (hazard ratio [HR] =1.51, 95% confidence interval [CI]: 1.07-2.13). When radiotherapy was further categorized by modalities (brachytherapy, conventional conformal radiotherapy, and intensity-modulated radiotherapy [IMRT]), increased risk of second MDS/AML was only observed in the IMRT group (HR = 1.66, 95% CI: 1.09-2.54).

CONCLUSIONS

Our findings suggest that radiotherapy for prostate cancer increases the risk of MDS/AML, and the impact may differ by modality. Additional studies with longer follow-up are needed to further clarify the role of radiotherapy in the development of subsequent myeloid malignancies. A better understanding may help patients, physicians, and other stakeholders make more informed treatment decisions. Prostate 77:437-445, 2017. © 2016 Wiley Periodicals, Inc.

Comparison of clinical outcomes and prognostic utility of risk stratification tools in patients with therapy-related vs de novo myelodysplastic syndromes: a report on behalf of the MDS Clinical Research Consortium

While therapy-related (t)-myelodysplastic syndromes (MDS) have worse outcomes than de novo MDS (d-MDS), some t-MDS patients have an indolent course. Most MDS prognostic models excluded t-MDS patients during development. The performances of the International Prognostic Scoring System (IPSS), revised IPSS (IPSS-R), MD Anderson Global Prognostic System (MPSS), WHO Prognostic Scoring System (WPSS) and t-MDS Prognostic System (TPSS) were compared among patients with t-MDS. Akaike information criteria (AIC) assessed the relative goodness of fit of the models. We identified 370 t-MDS patients (19%) among 1950 MDS patients. Prior therapy included chemotherapy alone (48%), chemoradiation (31%), and radiation alone in 21%. Median survival for t-MDS patients was significantly shorter than for d-MDS (19 vs 46 months, P<0.005). All models discriminated survival in t-MDS (P<0.005 for each model). Patients with t-MDS had a significantly higher hazard of death relative to d-MDS in every risk model, and had inferior survival compared to patients with d-MDS within all risk group categories. AIC Scores (lower is better) were 2316 (MPSS), 2343 (TPSS), 2343 (IPSS-R), 2361 (WPSS) and 2364 (IPSS). In conclusion, subsets of t-MDS patients with varying clinical outcomes can be identified using conventional risk stratification models. The MPSS, TPSS and IPSS-R provide the best predictive power.

Therapy-related myelodysplastic syndrome following primary breast cancer

BACKGROUND

Therapy-related myelodysplastic syndrome (t-MDS) is a serious clinical disease occurring after breast cancer treatment.

METHODS

A cohort of 11,684 invasive breast cancer (BC) patients from 1990-2014 were followed for incidence of t-MDS through institutional and the Surveillance, Epidemiology and End Results (SEER) Program registries. t-MDS cases were identified using ICD-O SEER registry codes, pathology and chart reports. Treatment, cytogenetics, and time from BC diagnosis to t-MDS and t-MDS diagnosis to last follow up or death were obtained. Incidence rate ratios were calculated using SEER national incidence rates for comparison.

RESULTS

27 cases of t-MDS post BC treatment were confirmed. 96% of cases were breast cancer stage I-II at diagnosis. All patients had received radiation treatment and 59% received adjuvant chemotherapy. Two patients were alive with no evidence of disease after treatment with stem cell transplantation (age 33 and 46). t-MDS incidence was 30 times the expected population rate among patients <55 years (RR 31.8, 95% CI 15.0, 60.8) with shorter time from t-MDS diagnosis to death (median survival time: <55: 8 months, 55-74: 26 months, 75+: 23 months).

CONCLUSION

We found elevated t-MDS risk especially among younger BC patients with stem cell transplantation the only observed curative treatment.

Myelodysplastic syndrome and acute myeloid leukemia following adjuvant chemotherapy with and without granulocyte colony-stimulating factors for breast cancer

Risk of myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML) post-breast cancer treatment with adjuvant chemotherapy and granulocyte colony-stimulating factors (G-CSF) is not fully characterized. Our objective was to estimate MDS/AML risk associated with specific breast cancer treatments. We conducted a retrospective cohort study of women aged ≥66 years with stage I-III breast cancer between 2001 and 2009 using the Surveillance, Epidemiology, and End Results-Medicare database. Women were classified as receiving treatment with radiation, chemotherapy, and/or G-CSF. We used multivariable Cox proportional hazards models to estimate adjusted hazard ratios (HR) and 95 % confidence intervals (CI) for MDS/AML risk. Among 56,251 breast cancer cases, 1.2 % developed MDS/AML during median follow-up of 3.2 years. 47.1 % of women received radiation and 14.3 % received chemotherapy. Compared to breast cancer cases treated with surgery alone, those treated with chemotherapy (HR = 1.38, 95 %-CI 0.98-1.93) and chemotherapy/radiation (HR = 1.77, 95 %-CI 1.25-2.51) had increased risk of MDS/AML, but not radiation alone (HR = 1.08, 95 % CI 0.86-1.36). Among chemotherapy regimens and G-CSF, MDS/AML risk was differentially associated with anthracycline/cyclophosphamide-containing regimens (HR = 1.86, 95 %-CI 1.33-2.61) and filgrastim (HR = 1.47, 95 %-CI 1.05-2.06), but not pegfilgrastim (HR = 1.10, 95 %-CI 0.73-1.66). We observed increased MDS/AML risk among older breast cancer survivors treated with anthracycline/cyclophosphamide chemotherapy that was enhanced by G-CSF. Although small, this risk warrants consideration when determining adjuvant chemotherapy and neutropenia prophylaxis for breast cancer patients.

Cell injury, retrodifferentiation and the cancer treatment paradox

This “opinion article” is an attempt to take an overview of some significant changes that have happened in our understanding of cancer status during the last half century and its evolution under the progressive influence of molecular biology. As an active worker in cancer research and developmental biology during most of this period, I would like to comment briefly on these changes and to give my critical appreciation of their outcome as it affects our knowledge of cancer development as well as the current treatment of the disease. A recall of my own contribution to the subject is also included. Two subjects are particularly developed: cell injury and cell-killing therapies. Cell injury, whatever its origin, has acquired the status of a pivotal event for the initiation of cancer emergence. It is postulated that cell injury, a potential case of cellular death, may also be the origin of a process of stepwise cell reversion (retrodifferentiation or retroprogrammation) leading, by division, mature or stem cells to progressive immaturity. The genetic instability and mutational changes that accompanies this process of cell injury and rejuvenation put normal cells in a status favourable to neoplastic transformation or may evolve cancer cells toward clones with higher malignant potentiality. Thus, cell injury suggests lifestyle as the major upstream initiator of cancer development although this not exclude randomness as an unavoidable contributor to the disease. Cell-killing agents (mainly cytotoxic drugs and radiotherapy) are currently used to treat cancer. At the same time, it is agreed that agents with high cell injury potential (ultraviolet light, ionising radiations, tobacco, environmental pollutants, etc.) contribute to the emergence of malignant tumours. This represents a real paradox. In spite of the progress accomplished in cancer survival, one is tempted to suggest that we have very few chances of really cure cancer as long as we continue to treat malignancies with cell-killing therapies. Indeed, the absence of alternatives to such treatments justifies the pursuit of current procedures of cancer care. But, this should be, precisely, an urgent stimulus to explore other therapeutic approaches. Tumour reversion, immunotherapy, stem cell management and genomic analysis of embryo-foetal development could be, among others, appropriated candidates for future active research.

Racial and ethnic differences in risk of second primary cancers among breast cancer survivors

Disparities exist in breast cancer (BC) outcomes between racial and ethnic groups in the United States. Reasons for these disparities are multifactorial including differences in genetics, stage at presentation, access to care, and socioeconomic factors. Less is documented on racial/ethnic differences in subsequent risk of second primary cancers (SPC). The purpose of this study is to evaluate the risk of SPC among different racial/ethnic groups of women with BC. We conducted a retrospective cohort study of 134,868 Non-Hispanic White, 17,484 Black, 18,034 Hispanic, and 19,802 Asian/Pacific Islander (API) women with stages I-III BC in twelve Surveillance, Epidemiology and End Results Program registries between 2001 and 2010. Standardized incidence ratios (SIR), 95 % confidence intervals (CI), and absolute excess risks were calculated by comparing incidence of SPC in the cohort to incidence in the general population for specific cancer sites by race/ethnicity and stratified by index BC characteristics. All women were at increased risks of second primary BC and acute myeloid leukemia (AML), with higher risk among more advanced stage index BC. Black and API women had higher SIRs for AML [4.86 (95 % CI 3.05-7.36) and 5.00 (95 % CI 3.26-7.32)], respectively] which remained elevated among early-stage (I) BC cases. Women with a history of invasive BC have increased risk of SPC, most notable for second primary BC and AML. These risks for secondary cancers differ by race/ethnicity. Studies evaluating possible genetic and biobehavioral mechanisms underlying these differences are warranted. Strategies for BC adjuvant treatment and survivorship care may require further individualization with consideration given to race/ethnicity.

Radiotherapy- and chemotherapy-induced myelodysplasia syndrome: a nationwide population-based nested case-control study

This study explored which kinds of cancer are related to a higher incidence of subsequent myelodysplastic syndrome (MDS) after radiotherapy (RT) and chemotherapy (CT).We performed a nested case-control study by using data from the Taiwanese National Health Insurance (NHI) system. The case group included cancer patients who developed MDS. For the control group, 4 cancer patients without MDS were frequency-matched with each MDS case by age, sex, year of cancer diagnosis, and MDS index year. A multivariable logistic regression analysis was conducted, and odds ratios (ORs) and 95% confidence intervals (CIs) were estimated.Overall, cancer patients who received RT or CT exhibited secondary MDS more frequently than did those who did not (RT: OR = 1.53; 95% CI = 1.33-1.77; CT: OR = 1.51; 95% CI = 1.25-1.82). Analysis by cancer site showed that RT increased the risk of MDS for patients with stomach, colorectal, liver, breast, endometrial, prostate, and kidney cancers. By contrast, CT was more likely to increase the risk of MDS for patients with lung, endometrial, and cervical cancers. Further analysis revealed that RT and CT seemed to have a positive interaction. The major limitation of this study was the lack of certain essential data in the NHI Research Database, such as data regarding cancer stage and treatment dose details.This population-based nested case-control study determined that RT and CT predisposed patients in Taiwan to the development of MDS. This effect was more prominent when both modalities were used.

Risk of marrow neoplasms after adjuvant breast cancer therapy: the national comprehensive cancer network experience

PURPOSE

Outcomes for early-stage breast cancer have improved. First-generation adjuvant chemotherapy trials reported a 0.27% 8-year cumulative incidence of myelodysplastic syndrome/acute myelogenous leukemia. Incomplete ascertainment and follow-up may have underestimated subsequent risk of treatment-associated marrow neoplasm (MN).

PATIENTS AND METHODS

We examined the MN frequency in 20,063 patients with stage I to III breast cancer treated at US academic centers between 1998 and 2007. Time-to-event analyses were censored at first date of new cancer event, last contact date, or death and considered competing risks. Cumulative incidence, hazard ratios (HRs), and comparisons with Surveillance, Epidemiology, and End Results estimates were obtained. Marrow cytogenetics data were reviewed.

RESULTS

Fifty patients developed MN (myeloid, n = 42; lymphoid, n = 8) after breast cancer (median follow-up, 5.1 years). Patients who developed MN had similar breast cancer stage distribution, race, and chemotherapy exposure but were older compared with patients who did not develop MN (median age, 59.1 v 53.9 years, respectively; P = .03). Two thirds of patients had complex MN cytogenetics. Risk of MN was significantly increased after surgery plus chemotherapy (HR, 6.8; 95% CI, 1.3 to 36.1) or after all modalities (surgery, chemotherapy, and radiation; HR, 7.6; 95% CI, 1.6 to 35.8), compared with no treatment with chemotherapy. MN rates per 1,000 person-years were 0.16 (surgery), 0.43 (plus radiation), 0.46 (plus chemotherapy), and 0.54 (all three modalities). Cumulative incidence of MN doubled between years 5 and 10 (0.24% to 0.48%); 9% of patients were alive at 10 years.

CONCLUSION

In this large early-stage breast cancer cohort, MN risk after radiation and/or adjuvant chemotherapy was low but higher than previously described. Risk continued to increase beyond 5 years. Individual risk of MN must be balanced against the absolute survival benefit of adjuvant chemotherapy.

Age related risk of myelodysplastic syndrome and acute myeloid leukemia among breast cancer survivors

Increased incidence of acute myeloid leukemia (AML) has been identified among breast cancer (BC) survivors but measurement has not included myelodysplastic syndrome (MDS). Our aim is to identify age and stage related MDS/AML incidence post BC diagnosis. We used the 2001-2009 Surveillance, Epidemiology, and end results (SEER) database to identify first primary stage I-III BC patients. Subsequent MDS or AML diagnosis was identified with observed rates compared to expected MDS/AML incidence in the general population. Age adjusted observed/expected rate ratios and 95 % confidence intervals (CI) were calculated. The unadjusted all age and stage MDS/AML incidence rate was .15 % (470/306,691) with a progressively higher rate by age (age 20-49 = .11, age 50-64 = .14, age 65+ =.21, and age 75+ =.18) and stage (stage I = .11, stage II = .18, and stage III = .22). Compared to the general population, BC patients had a 2.75-fold [95 % CI 2.51-3.00] increased relative risk of being diagnosed with MDS/AML. Young age survivors had highest relative risk [age 20-49: relative risk (RR) = 10.60 (95 % CI 8.57-12.93); age 50-64: 5.96 (95 % CI 5.13, 6.88); age 65-74 year-olds: 2.94 (95 % CI 2.45, 3.50); and age ≥75 year-olds: 1.28 (95 % CI 1.03, 1.56)]. Separately MDS relative risk was highest among young women [30.44 (95 % CI = 19.63, 44.62)]. MDS/AML relative risk increased from 1.87 to 5.66 for stage I-III.

CONCLUSIONS

Myelodysplastic syndrome and acute myeloid leukemia relative risk is substantially elevated among breast cancer survivors especially those aged 20-49. While the actual number is small, MDS/AML is a serious disease. More research is needed to identify the treatments that put women at risk and find less leukemogenic options, especially for young women.