Therapy-related leukemia associated with alkylating agents

Molecular signaling and clinical implications in the human aging-cancer cycle

It is well documented that aging is associated with cancer, and likewise, cancer survivors display accelerated aging. As the number of aging individuals and cancer survivors continues to grow, it raises additional concerns across society. Therefore, unraveling the molecular mechanisms of aging in tissues is essential to developing effective therapies to fight the aging and cancer diseases in cancer survivors and cancer patients. Indeed, cellular senescence is a critical response, or a natural barrier to suppress the transition of normal cells into cancer cells, however, hypoxia which is physiologically required to maintain the stem cell niche, is increased by aging and inhibits senescence in tissues. Interestingly, oxygen restriction or hypoxia increases longevity and slows the aging process in humans, but hypoxia can also drive angiogenesis to facilitate cancer progression. In addition, cancer treatment is considered as one of the major reasons that drive cellular senescence, subsequently followed by accelerated aging. Several clinical trials have recently evaluated inhibitors to eliminate senescent cells. However, some mechanisms of aging typically can also retard cancer cell growth and progression, which might require careful strategy for better clinical outcomes. Here we describe the molecular regulation of aging and cancer in crosstalk with DNA damage and hypoxia signaling pathways in cancer patients and cancer survivors. We also update several therapeutic strategies that might be critical in reversing the cancer treatment-associated aging process.

The Achilles' heel of cancer survivors: fundamentals of accelerated cellular senescence

Recent improvements in cancer treatment have increased the lifespan of pediatric and adult cancer survivors. However, cancer treatments accelerate aging in survivors, which manifests clinically as the premature onset of chronic diseases, such as endocrinopathies, osteoporosis, cardiac dysfunction, subsequent cancers, and geriatric syndromes of frailty, among others. Therefore, cancer treatment-induced early aging accounts for significant morbidity, mortality, and health expenditures among cancer survivors. One major mechanism driving this accelerated aging is cellular senescence; cancer treatments induce cellular senescence in tumor cells and in normal, nontumor tissue, thereby helping mediate the onset of several chronic diseases. Studies on clinical monitoring and therapeutic targeting of cellular senescence have made considerable progress in recent years. Large-scale clinical trials are currently evaluating senotherapeutic drugs, which inhibit or eliminate senescent cells to ameliorate cancer treatment-related aging. In this article, we survey the recent literature on phenotypes and mechanisms of aging in cancer survivors and provide an up-to-date review of the major preclinical and translational evidence on cellular senescence as a mechanism of accelerated aging in cancer survivors, as well as insight into the potential of senotherapeutic drugs. However, only with time will the clinical effect of senotherapies on cancer survivors be visible.

Treatment-related leukemia after taxane and platinum therapy in gynecological cancer patients (Gynecologic Oncology Trial and Investigation Consortium 011)

AIM

To clarify incidence and clinical features of treatment-related leukemia (TRL) due to taxane/platinum therapy in gynecological cancer patients.

METHODS

We conducted a retrospective study of gynecological cancer patients who were diagnosed at facilities participating in the Gynecologic Oncology Trial and Investigation Consortium and started only taxane/platinum therapy as chemotherapy between 2002 and 2006.

RESULTS

The site of the primary lesion was the ovary in 124, endometrium in 37, and uterine cervix in 4. The regimen of chemotherapy was paclitaxel (T) + carboplatin (C) therapy in 134 and others in 31 patients. The cumulative incidence was 2.4% (4/165), and the incidence was 2.9/1,000 person-years. All four cases were acute myeloid leukemia. The average total doses of T and C in patients without TRL were 1,693 (SD 1,050) and 4,170 (SD 2,423) mg. For TRL patients, the total T and C doses were, respectively, 1,555 and 3,540 mg, 1,620 and 4,200 mg, 2,130 and 4,700 mg, 3,220 mg and 8,310 mg. The fourth patient received additional 2,415 mg of docetaxel and 2,155 mg of nedaplatin. The intervals from the primary chemotherapy to the onset of TRL were 27, 34, 67, and 114 months. Three patients had no evidence of ovarian cancer. Three patients died of TRL at 4 days, 5 months, and 11 months, one patient remained in remission at 25 months after diagnosis of TRL.

CONCLUSION

Patients receiving taxane/platinum therapy should undergo long-term follow-up with attention to the development of TRL, even if the gynecologic malignant cancer is in remission.

Cancer Treatment-Induced Accelerated Aging in Cancer Survivors: Biology and Assessment

Rapid improvements in cancer survival led to the realization that many modalities used to treat or control cancer may cause accelerated aging in cancer survivors. Clinically, "accelerated aging" phenotypes in cancer survivors include secondary cancers, frailty, chronic organ dysfunction, and cognitive impairment, all of which can impact long-term health and quality of life in cancer survivors. The treatment-induced accelerated aging in cancer survivors could be explained by telomere attrition, cellular senescence, stem cell exhaustion, DNA damage, and epigenetic alterations. Several aging clocks and biomarkers of aging have been proposed to be potentially useful in estimating biological age, which can provide specific information about how old an individual is biologically independent of chronological age. Measuring biological age in cancer survivors may be important for two reasons. First, it can better predict the risk of cancer treatment-related comorbidities than chronological age. Second, biological age may provide additional value in evaluating the effects of treatments and personalizing cancer therapies to maximize efficacy of treatment. A deeper understanding of treatment-induced accelerated aging in individuals with cancer may lead to novel strategies that reduce the accelerated aging and improve the quality of life in cancer survivors.

Role of radiotherapy and chemotherapy in the risk of leukemia after childhood cancer: An international pooled analysis

Childhood cancer survivors are at increased risk for second primary leukemia (SPL), but there is little consensus on the magnitude of some risk factors because of the small size of previous studies. We performed a pooled analysis of all published studies with detailed treatment data, including estimated active bone marrow (ABM) dose received during radiation therapy and doses of specific chemotherapeutic agents for childhood cancer diagnosed from 1930 through 2000, in order to more thoroughly investigate treatment-related risks of SPL. A total of 147 SPL cases (of which 69% were acute myeloid leukemia [AML]) were individually matched to 522 controls, all from four case-control studies including patients from six countries (France, United Kingdom, United States, Canada, Italy and Netherlands). Odds ratios (OR) and corresponding 95% confidence intervals (CIs) were calculated using conditional logistic regression, and the excess OR per Gray (EOR/Gy) was also calculated. After accounting for the other therapies received, topoisomerase II inhibitor was associated with an increased SPL risk (highest tertile vs none: OR = 10.0, 95% CI: 3.7-27.3). Radiation dose to the ABM was also associated with increased SPL risk among those not receiving chemotherapy (EOR/Gy = 1.6, 95% CI: 0.1-14.3), but not among those who received chemotherapy (CT). SPL were most likely to occur in the first decade following cancer treatment. Results were similar when analyses were restricted to AML. The evidence of interaction between radiation and CT has implications for leukemogenic mechanism. The results for topoisomerase II inhibitors are particularly important given their increasing use to treat childhood cancer.

Myeloid malignancies after treatment for solid tumours

The cure rate for several solid tumour malignancies including breast cancers, head and neck cancers, bone cancers, and sarcoma has improved remarkably with the advent of neoadjuvant and adjuvant therapies. Unfortunately, exposure to chemotherapy or radiation as a part of these treatments exposes patients to the risk of subsequent myeloid malignancies. Therapy related myeloid malignancies have certain characteristic findings. They typically arise within 10 years of treatment exposure, they are seen in younger patients, and the greatest risk is in patients who receive therapy with alkylating agents or topoisomerase II inhibitors. Solid tumours whose therapies utilize these agents at higher doses, namely bone/soft tissue cancers, testicular cancer, anal cancer, and brain tumours, appear to be the groups at highest risk for T-MN. Beyond these patients, emerging populations diagnosed with T-MN include prior platinum exposure, and patients requiring G-CSF support with chemotherapy.

Impact of cyclophosphamide and etoposide on outcome of clear cell sarcoma of the kidney treated on the National Wilms Tumor Study-5 (NWTS-5)

PURPOSE

To improve the event-free survival (EFS) and overall survival (OS) for patients with clear cell sarcoma of the kidney (CCSK) by incorporating cyclophosphamide and etoposide into treatment on National Wilms Tumor Study (NWTS)-5.

PATIENTS AND METHODS

Patients less than 16 years of age with a centrally confirmed pathological diagnosis of CCSK were eligible for treatment on this prospective single-arm study conducted between August 1995 and June 2002. Staging consisted of CT scans of chest, abdomen, pelvis, bone scan, skeletal survey, and CT or MRI of the head. Treatment consisted of vincristine/doxorubicin/cyclophosphamide alternating with cyclophosphamide/etoposide for 24 weeks and radiation to sites of disease.

RESULTS

One hundred eight eligible patients were enrolled on study (69% males, 63% Caucasian), with a median age of 22 months. Stage distribution was as follows: stage I, 12; II, 44; III, 45; IV, 7. Median follow-up was 9.7 years. Five-year EFS and OS were 79% (95% CI: 71%-88%) and 90% (95% CI: 84%-96%). Five-year EFS for stage I-IV was 100%, 88%, 73%, and 29%, respectively. Twenty of the 23 disease-related events occurred within three years of initial treatment. The most common site of recurrence was brain (12/23).

CONCLUSION

The outcome for patients with CCSK treated on NWTS-5 was similar to NWTS-4 and accomplished over a shorter treatment duration. Stage was highly predictive of outcome. Brain metastases occurred more frequently than on NWTS-4. Regimen I showed more benefit for patients with stage I and II disease as compared with higher stages of disease where new therapies are needed.

Review of risk factors of secondary cancers among cancer survivors

Improvements in cancer survival have made the long-term risks from treatments more important, in particular among the children, adolescents and young adults who are more at risk particularly due to a longer life expectancy and a higher sensitivity to treatments. Subsequent malignancies in cancer survivors now constitute 15 to 20% of all cancer diagnoses in the cancer registries. Lots of studies are published to determine risk factors, with some controversial findings. Just data from large cohorts with detailed information on individual treatments and verification of what is called "secondary cancers" can add some knowledge, because their main difficulty is that the number of events for most second cancer sites are low, which impact the statistical results. In this review of the literature, we distinguish second and secondary cancers and discuss the factors contributing to this increased risk of secondary cancers. The article concludes with a summary of current surveillance and screening recommendations.

[Secondary cancers: Incidence, risk factors and recommendations]

Cure rates for most childhood cancers and adolescents have made remarkable progress over the last thirty to forty years. The development of secondary malignancies has become an important question for these patients. The frequency is low, but the risk is significantly higher (between 3 and 10 times) and it is the leading cause of long-term mortality off relapse. In this literature review, we discuss the epidemiological aspect and the risk factors contributing to this increased risk, and conclude with a summary of current recommendations for screening and surveillance. We also discuss briefly the constitutional predisposing genetic contributions to other cancers.

Secondary malignancies in pediatric cancer survivors: perspectives and review of the literature

With continuing improvements in the successful treatment of pediatric malignancies, long term survivors of pediatric cancers and their providers are faced with new oncologic issues regarding long-term morbidities. As pediatric cancer survivors have matured into adulthood, the development of secondary malignancies has become a significant issue for these patients. Whether a consequence of treatment for the patient's original cancer, such as chemotherapy, ionizing radiation, or hematopoietic stem cell transplantation, secondary malignancies now present patients and providers with new challenges regarding treatment, surveillance and counseling. We review the major risk factors for secondary malignancies in pediatric cancer survivors, with particular emphasis on important molecular and cytogenetic risk factors, both inherited and acquired. We conclude with a discussion of recommendations for surveillance and counseling of these patients.

Incidence, survival and prevalence of myeloid malignancies in Europe

BACKGROUND

The Surveillance of Rare Cancers in Europe (RARECARE) project aims at increasing knowledge of rare cancers in Europe. This manuscript describes the epidemiology of myeloid malignancies (MMs), taking into account the morphological characterisation of these tumours.

METHODS

We used data gathered by RARECARE on cancer patients diagnosed from 1995 to 2002 and archived in 64 European population-based cancer registries, followed up to 31st December 2003 or later.

RESULTS

The overall annual crude incidence of MMs was 8.6 per 100,000. Acute myeloid leukaemia (AML) and myeloproliferative neoplasms (MPN) were most common, with incidence rates of 3.7 and 3.1 per 100,000 year respectively, followed by 1.8 for myelodysplastic syndromes (MDS) and myelodysplastic/myeloproliferative neoplasms (MD/MPN) and 0.1 for histiocytic and dendritic cell neoplasms (HDCN). The 5-year relative survival rate ranged from 18% for chronic myelomonocytic leukaemia, 19% for AML, 29% for MDS and 44% for chronic myeloid leukaemia to relatively favourable rates for MPN (62%) and HDCN (83%). Total number of new cases of MMs in the EU27 is estimated at 43,000 annually, total number of prevalent cases (1st January 2008) at 189,000 cases.

CONCLUSION

MMs form a large variety of rare entities with specific characteristics. Collection of detailed information (immunophenotype, genetic abnormalities, molecular data and clinical data) and an up-to-date classification system is essential for their surveillance, especially now that more and more targeted therapies are being introduced.

Treatment-related myelodysplasia in patients with primary brain tumors

Treatment-related myelodysplastic syndrome (t-MDS) and treatment-related acute myelogenous leukemia (t-AML) represent rare secondary events in patients with primary tumors of the nervous system and predominantly affect those treated with alkylating agents or topoisomerase II inhibitors. Temozolomide has become the standard chemotherapeutic agent for malignant gliomas. The emergence of this alkylating agent with little acute toxicity or cumulative myelosuppression has led to off-label protracted chemotherapy for many patients with malignant and even low-grade infiltrative gliomas, raising concern for increased risk of t-MDS/t-AML in the few long-term survivors. On the basis of an extensive literature search, we provide a discussion of epidemiology, pathogenesis, clinical presentation, diagnosis, and therapy of these disorders. t-MDS/t-AML remain rare complications of chemotherapy in patients with primary brain tumors, and the vast majority of patients die of their primary neoplasm. Prospective randomized studies with long-term follow-up are required to accurately assess the risk of t-MDS/t-AML; however, unless survival in the most common gliomas substantially increases, t-MDS/t-AML incidence will likely remain low in this patient population.

Secondary malignant neoplasms after childhood cancer

Overall survival from cancer has greatly improved, although it still remains the second leading cause of mortality in the world. This result was achieved through the use of chemotherapy and radiotherapy, which are severely toxic to normal tissues. In the long-term follow-up of cancer patients, the development of secondary malignant disease is common and it is one of the most severe side effects of cancer treatment. Physicians aim to decrease this toxicity and reduce the development of secondary cancers. In this study, the epidemiology and etiology of second malignant neoplasms are reviewed.

Treatment of Ewing sarcoma family of tumors with a modified P6 protocol in children and adolescents

BACKGROUND

Reported overall survival (OS) rates of patients with localized Ewing sarcoma family of tumors (ESFT) are >80% when treated with the MSKCC P6 protocol. However, it has been associated with a 5.8% incidence of secondary leukemias. A modified P6 (mP6) protocol with reduced exposure to chemotherapy is presented.

PROCEDURE

Thirty-one newly diagnosed ESFT patients were enrolled onto this phase II, single-arm, non-randomized protocol. Courses 1, 2 and 4 consisted of cyclophosphamide 4.2 g/m², doxorubicin 75 mg/m², and vincristine 2 mg/m² (CDV). Cycles 3 and 5 consisted of ifosfamide 9 g/m² and etoposide 500 mg/m² (IE). Course 5 ifosfamide was 14 g/m² if necrosis was <90%.

RESULTS

Twenty-four patients had loco-regional disease and seven had metastases. The 4-year event-free survival (EFS) rate for patients with localized tumors is 83% and overall survival (OS) is 92%. The 3-year EFS rate for patients with distant metastases is 28% and OS rate is 42%. EWS-FLI1 fusion genes were detected in 17 cases (74%) and EWS-ERG in six cases (26%). Type 1 EWS-FLI1 variant was present in 6/7 metastatic patients and 3/16 loco-regional cases (P = 0.001). None of the patients experienced tumor progression before remission. All relapses occurred within 2 years from the end of treatment and local relapses (n = 3) happened in patients who did not receive radiation therapy. No secondary malignancies have been observed, median follow-up of 4.3 years for surviving patients.

CONCLUSIONS

In this pilot study, the mP6 protocol produced a complete remission rate of 83% at 4 years in non-metastatic ESFT reducing the risk of secondary malignancies.

Secondary neoplasms after retinoblastoma treatment: retrospective cohort study of 754 patients in Japan

OBJECTIVE

Little is known about the incidence of secondary neoplasms among survivors of retinoblastoma in Japan. The objective of our study was to analyze the cumulative incidence rate of secondary neoplasms following retinoblastoma and to investigate the risk factors of developing secondary neoplasms.

METHODS

We conducted a retrospective cohort study of 754 retinoblastoma patients who visited the National Cancer Center Hospital in Tokyo between 1964 and 2007. The cumulative incidence rate curves were drawn using the competing risk method and compared with the Gray's test. Using competing risk regression analysis, multivariate analysis estimated the subdistribution hazard ratio of factors related to the development of secondary neoplasms.

RESULTS

The median length of follow-up was 108 months (0-594 months). Twenty-one (2.8%) patients developed 23 secondary neoplasms in total. The cumulative incidence rates of secondary neoplasms after retinoblastoma treatment were 2.4% at 10 years after diagnosis, 4.3% at 20 years, 6.4% at 30 years and 19.1% at 40 years. Ten patients (1.3%) died and 723 (95.9%) were alive without developing secondary neoplasms. The subdistribution hazard ratios of hereditary retinoblastoma and external beam irradiation were 4.85 (95% confidence interval = 0.74-31.85) and 4.76 (95% confidence interval = 0.69-33.09), respectively.

CONCLUSIONS

We demonstrated the cumulative incidence rate of secondary neoplasms following retinoblastoma in Japan. The subdistribution hazards ratios of hereditary retinoblastoma and external beam irradiation were high but not significant because of statistical power. The long-term follow-up of retinoblastoma survivors is warranted to understand secondary neoplasm risk.

Phase I study of temozolomide combined with oral etoposide in children with recurrent or progressive medulloblastoma

BACKGROUND

The prognosis of recurrent or progressive medulloblastoma (MB) is still poor. This study was designed to investigate the potential therapeutic benefit of combination therapy with temozolomide (TMZ) and oral etoposide (VP-16) in children with progressive or relapsed MB. Given the oral administration of both drugs the regimen was administered outpatient.

METHODS

A phase I trial was conducted to establish the maximum tolerated dose (MTD) of TMZ and oral VP-16. This orally administered combination was investigated by classical 3+3 design. Cohorts of patients were enrolled at four different levels: (1) TMZ 120 mg/m(2) on days 1-5 and VP-16 50 mg/m(2) on days 1-8; (2) TMZ 150 mg/m(2) on days 1-5 and VP-16 50 mg/m(2) on days 1-8; (3) TMZ 150 mg/m(2) on days 1-5 and VP-16 50 mg/m(2) on days 1-10; (4) TMZ 150 mg/m(2) on days 1-5 and VP-16 50 mg/m(2) on days 1-12. Therapy was administered in 28-d courses. A total of 66 courses were administered to 14 patients with a median age of 5.7 years.

RESULTS

None of the 3 patients at dose levels 1 and 2 had dose-limiting toxicity (DLT). Of the 6 patients at dose level 3, 1 patient had DLT. At dose level 4, grade 4 thrombocytopaenia and neutropaenia were observed in the first 2 patients enrolled. Therefore, the MTD was established at dose level 3.

CONCLUSION

The recommended phase II dose in children is TMZ 150 mg/m(2) on days 1-5 and VP-16 50 mg/m(2) on days 1-10 every 28 d. The combination was well tolerated and demonstrated antitumour activity.

Molecular biology of therapy-related leukaemias

Therapy-related leukaemias are becoming an increasing healthcare problem as more patients survive their primary cancers. The nature of the causative agent has an important bearing upon the characteristics, biology, time to onset and prognosis of the resultant leukaemia. Agents targeting topoisomerase II induce acute leukaemias with balanced translocations that generally arise within 3 years, often involving the MLL, RUNX1 and RARA loci at 11q23, 21q22 and 17q21 respectively. Chromosomal breakpoints have been found to be preferential sites of topoisomerase II cleavage, which are believed to be repaired by the nonhomologous end-joining DNA repair pathway to generate chimaeric oncoproteins that underlie the resultant leukaemias. Therapy-related acute myeloid leukaemias occurring after exposure to antimetabolites and/or alkylating agents are biologically distinct with a longer latency period, being characterised by more complex karyotypes and loss of p53. Although treatment of therapy-related leukaemias represents a considerable challenge due to prior therapy and comorbidities, curative therapy is possible, particularly in those with favourable karyotypic features.

Reduced risk of secondary leukemia with fewer cycles of dose-intensive induction chemotherapy in patients with neuroblastoma

BACKGROUND

We report a prospective study of secondary leukemia (SL)/myelodysplastic syndrome (MDS) in neuroblastoma (NB) patients treated with > or =5 cycles of dose-intensive chemotherapy.

PROCEDURE

NB patients received induction with high-dose cyclophosphamide (4,200 mg/m(2))-doxorubicin (75 mg/m(2))-vincristine (cycles 1, 2, 4, 6, 8), and high-dose cisplatin (200 mg/m(2))-etoposide (600 mg/m(2)) (cycles 3, 5, 7). Bone marrow was examined every 1-3 months for > or =36 months, with inclusion of extensive chromosomal studies 1-3 months post-induction and 1-2x/year thereafter.

RESULTS

One hundred eight four patients received 5 (n = 76), 6 (n = 45), 7 (n = 59), or 8 (n = 4) cycles. Eight patients developed SL/MDS (only one each in the 5- and 6-cycle groups), at 12-50 months, including two cases detected in surveillance studies. Among 108 patients who received > or =6 cycles, the 5-year cumulative incidence was 7.1% (95% CI: 2%, 12.2%), versus 0% among 54 patients who received 5 cycles without maintenance oral etoposide. Five-year cumulative incidences were 1.46%, 2.28%, and 8.47% among patients in the 5-, 6-, and 7-cycle groups, with fewer cycles having a significantly lower risk (P = 0.048). There was no significant association of risk with potentially leukemogenic consolidative treatments (targeted radiotherapy, myeloablative therapy, and oral etoposide).

CONCLUSIONS

Reducing the number of dose-intensive cycles significantly decreases the risk of SL/MDS, yielding 5-year rates matching the low range (0.4-2.2%) reported for moderate-dose combination chemotherapy regimens used against other pediatric solid tumors.

Acute leukemia as a secondary malignancy in children and adolescents: current findings and issues

Secondary acute leukemia is a devastating complication in children and adolescents who have been treated for cancer. Secondary acute lymphoblastic leukemia (s-ALL) was rarely reported previously but can be distinguished today from recurrent primary ALL by comparison of immunoglobulin and T-cell receptor rearrangement. Secondary acute myeloid leukemia (s-AML) is much more common, and some cases actually may be second primary cancers. Treatment-related and host-related characteristics and their interactions have been identified as risk factors for s-AML. The most widely recognized treatment-related risk factors are alkylating agents and topoisomerase II inhibitors (epipodophyllotoxins and anthracyclines). The magnitude of the risk associated with these factors depends on several variables, including the administration schedule, concomitant medications, and host factors. A high cumulative dose of alkylating agents is well known to predispose to s-AML. The prevalence of alkylator-associated s-AML has diminished among pediatric oncology patients with the reduction of cumulative alkylator dose and limited use of the more leukemogenic alkylators. The best-documented topoisomerase II inhibitor-associated s-AML is s-AML associated with epipodophyllotoxins. The risk of s-AML in these cases is influenced by the schedule of drug administration and by interaction with other antineoplastic agents but is not consistently found to be related to cumulative dose. The unpredictable risk of s-AML after epipodophyllotoxin therapy may discourage the use of these agents, even in patients at a high risk of disease recurrence, although the benefit of recurrence prevention may outweigh the risk of s-AML. Studies in survivors of adult cancers suggest that, contrary to previous beliefs, the outcome of s-AML is not necessarily worse than that of de novo AML when adjusted for cytogenetic features. More studies are needed to confirm this finding in the pediatric patient population.

Acute lymphoblastic leukemia secondary to chemoradiotherapy for perivascular epithelioid cell tumor of uterus

Acute lymphoblastic leukemia (ALL), a primary hematologic malignancy that is especially common in childhood, occurs relatively rarely as a secondary malignant neoplasm. Available data indicate that ALL often follows chemoradiotherapy for soft tissue sarcoma. Perivascular epithelioid tumor (PEComa), a primitive mesenchymal tissue origin, can be classified as a soft tissue sarcoma. An 11-year-old girl was diagnosed with ALL secondary to chemoradiotherapy (vincristine, ifosfamide, and anthracycline) and radiotherapy comprising 45 Gy to the whole pelvis for PEComa. ALL, FAB L2, and immunophenotypically pro-B developed 16 months after the final chemotherapy treatment. Moreover, a cytogenetic study of lymphoblasts showed t(1;11)(p32;q23). Herein, the authors report a case of secondary ALL that might be related to a previously used intercalating DNA topoisomerase II inhibitor (anthracycline) for a very rare sarcoma, PEComa.

Carcinogenic effect of an antitumor drug etoposide in laboratory animals

Intravenous injection of antitumor drug etoposide in the maximum tolerated dose was followed by the development of breast cancer in 38.1% female Wistar rats and 6.7% female outbred mice.

Recurrent metastatic neuroblastoma followed by myelodysplastic syndrome: possible leukemogenic role of temozolomide

An 8-year old child had a pelvic MYCN-nonamplified neuroblastoma (NB) with retroperitoneal nodal extension. Multi-modality therapy achieved complete remission (CR). Small recurrences confined to left supraclavicular nodes were treated with surgery alone at 4.9, 6.5, 7.5, 9.5, and 12.9 years from diagnosis. Monitoring through 12 months after the last resection showed CR. When she returned 34 months later (16.8 years from diagnosis), she had massive disease in the left neck and upper trunk, without osteomedullary metastases. Salvage therapy featured 11 cycles of temozolomide. She developed myelodysplastic syndrome with 45,XX,der(7)t(7;21) (p15;q11),-21 at age 24 and refused treatment; 19 months later she was transfusion-dependent but her NB remained in CR.

Myelodysplastic syndrome in children and adolescents

Myelodysplastic syndromes (MDS) are clonal disorders characterized by ineffective hematopoiesis and subsequent frequent development of acute myeloid leukemia (AML). In children and adolescents, MDS are uncommon disorders, accounting for less than 5% of hematopoietic malignancy, with great heterogeneity in presentation and clinical course. The genetic changes predisposing children to MDS are largely obscure. Monosomy 7 is the most common chromosomal abnormality, often occurring as a sole abnormality. The recent pediatric modification of the World Health Organization (WHO) classification has greatly facilitated the diagnostic process. Refractory cytopenia (RC) is the most common MDS subtype in children, occurring in about half of all MDS cases. There is consensus that the relationship between MDS with increased blast count and de novo AML is better defined by biological and clinical features than by blast count. Because monosomy 7 is the only chromosomal abnormality strongly suggestive of MDS, children presenting with a low blast count and other chromosomal aberrations or normal karyotype must be closely observed before a diagnosis of MDS can be established. With an increasing number of children surviving primary cancer with chemotherapy or radiation therapy, the incidence of secondary therapy-related MDS is rising. The MDS risk is also increased in patients with inherited bone marrow failure disorders; this relationship provides valuable insights into MDS biology. Allogeneic hematopoietic stem cell transplantation (HSCT) from a matched related or suitable unrelated donor is the choice for most children with MDS and can rescue a large proportion of patients.

Secondary acute myelogenous leukemia in patients with retinoblastoma: is chemotherapy a factor?

PURPOSE

To describe a series of patients with secondary acute myelogenous leukemia (sAML) and retinoblastoma (RB).

DESIGN

Retrospective observational cases series.

PARTICIPANTS

Ocular and pediatric oncologists at referral centers in Europe and the Americas and the RB databases at the National Institutes of Health and the Ophthalmic Oncology Service at Memorial Sloan-Kettering Cancer Center.

METHODS

Physician survey, retrospective database review, and literature search.

MAIN OUTCOME MEASURES

History of RB and development of sAML, management of RB (surgery, radiotherapy, chemotherapy), age at diagnosis of RB and leukemia, French-American-British (FAB) subtype, and current status of patient (alive or dead).

RESULTS

Fifteen patients with sAML were identified; 13 occurred in childhood. Mean latent period from RB to AML diagnosis was 9.8 years (median, 42 months). Nine cases were of the M2 or M5 FAB subtypes. Twelve patients (79 %) had received chemotherapy with a topoisomerase II inhibitor, 8 (43%) had received chemotherapy with an epipodophyllotoxin. Ten children died of their leukemia.

CONCLUSIONS

Acute myelogenous leukemia is a rare secondary malignancy among retinoblastoma patients, many of whom were treated with primary or adjuvant chemotherapy. Additional studies are needed to assess potential risk factors contributing to sAML development in this cohort.

O6-methylguanine-DNA-methyltransferase (MGMT) gene therapy targeting haematopoietic stem cells: studies addressing safety issues

As haematopoietic stem cell gene therapy utilizing O(6)-methylguanine-DNA-methyltransferase has reached the clinical stage, safety-related questions become increasingly important. These issues concern insertional mutagenesis of viral vectors, the acute toxicity of pre-transplant conditioning protocols and in vivo selection regimens as well as potential genotoxic side effects of the alkylating drugs administered in this context. To address these questions, we have investigated toxicity-reduced conditioning regimens combining low-dose alkylator application with sublethal irradiation and have analysed their influence on engraftment and subsequent selectability of transduced haematopoietic stem cells. In addition, a strategy to monitor the acute and long-term genotoxic effects of drugs with high guanine-O(6) alkylating potential, such as chloroethylnitrosoureas or temozolomide is introduced. For this purpose, assays were implemented which allow an assessment of the generation and fate of primary drug-induced adducts as well as their long-term effect on chromosomal integrity at the single cell level.

Role of MGMT in protecting against cyclophosphamide-induced toxicity in cells and animals

O(6)-Methylguanine-DNA methyltransferase (MGMT) is a DNA repair protein that protects cells from the biological consequences of alkylating agents by removing alkyl groups from the O(6)-position of guanine. Cyclophosphamide and ifosfamide are oxazaphosphorines used clinically to treat a wide variety of cancers; however, the role of MGMT in recognizing DNA damage induced by these agents is unclear. In vitro evidence suggests that MGMT may protect against the urotoxic oxazaphosphorine metabolite, acrolein. Here, we demonstrate that Chinese hamster ovary cells transfected with MGMT are protected against cytotoxicity following treatment with chloroacetaldehyde (CAA), a neuro- and nephrotoxic metabolite of cyclophosphamide and ifosfamide. The mechanism by which MGMT recognizes damage induced by acrolein and CAA is unknown. CHO cells expressing a mutant form of MGMT (MGMT(R128A)), known to have >1000-fold less repair activity towards alkylated DNA while maintaining full active site transferase activity towards low molecular weight substrates, exhibited equivalent CAA- and acrolein-induced cytotoxicity to that of CHO cells transfected with plasmid control. These results imply that direct reaction of acrolein or CAA with the active site cysteine residue of MGMT, i.e. scavenging, is unlikely a mechanism to explain MGMT protection from CAA and acrolein-induced toxicity. In vivo, no difference was detected between Mgmt-/- and Mgmt+/+ mice in the lethal effects of cyclophosphamide. While MGMT may be important at the cellular level, mice deficient in MGMT are not significantly more susceptible to cyclophosphamide, acrolein or CAA. Thus, our data does not support targeting MGMT to improve oxazaphosphorine therapy.

The late effects of childhood cancer therapy

In this article the difficulties that face survivors of childhood cancer therapy are presented, and the late effects of such therapy, separated into nonmalignant and malignant late effects, are discussed according to organ system. Recommendations for monitoring the late effects are set forth. A table listing radiation-therapy site and chemotherapeutic agents and selected late effects that result from their use is provided. Finally, a brief recommendation regarding the establishment of a late-effects clinic is also presented.

Does autologous transplantation directly increase the risk of secondary leukemia in lymphoma patients?

Patients who undergo autologous stem cell transplantation (ASCT) for lymphoma have a significant risk of therapy-related acute myeloid leukemia and myelodysplasia (t-AML/MDS). Compared to that seen in other indications such as breast cancer, multiple myeloma or germ cell tumors, there is a substantially increased risk for t-AML/MDS following ASCT for lymphoma. This risk has largely been attributed to the extent of pre-transplant chemotherapy and radiation therapy. In many of the larger series to date, it has not been possible to directly implicate autologous transplantation itself as a risk factor for t-AML/MDS. Although pre-transplant therapy is certainly an important factor in the development of t-AML/MDS, specific components of the autologous transplantation procedure itself may also contribute to the risk of t-AML/MDS. Specifically, priming chemotherapy, total body irradiation, and the extensive cellular proliferation which occurs during engraftment may all play a role in the development of t-AML/MDS. Furthermore, there is an increasing body of evidence that certain inherited polymorphisms in genes governing drug metabolism, DNA repair and leukemogenesis may influence susceptibility to t-AML/MDS. In this paper, we review the evidence implicating the above risk factors for t-AML/MDS, present a potential mechanism for t-AML/MDS and propose interventions to reduce the rate of t-AML/MDS in lymphoma patients.

Second neoplasms in pediatric patients treated for cancer: a center's 30-year experience

To investigate the incidence and outcome of secondary neoplasms in pediatric patients treated for childhood cancer. Between December 1971 and January 2000, a total of 5859 patients younger than age 17 were diagnosed and treated for childhood cancers in our center. Of this group, 1511 (36%) patients were followed for more than 36 months. These long-term survivors were included in this analysis. Twenty-six patients developed a secondary malignancy with an overall risk of 1.7% in this cohort. The male:female ratio was 17:10, with a median age of 7.66 at diagnosis (range, 2 to 16 y). Four patients (14.8%) with Hodgkin lymphoma; 3 each (11.1%) with retinoblastoma and rhabdomyosarcoma; 2 each (7.4%) with Wilms tumor, Ewing sarcoma, medulloblastoma, ganglioneuroblastoma, and non-Hodgkin lymphoma; and 1 each (3.7%) with ependymoma, nasopharyngeal carcinoma, osteosarcoma, astrocytoma had a secondary malignant disease during the long-term follow-up period. Secondary malignant diseases were osteosarcoma in 6 patients, acute lymphoblastic leukemia in 2, acute myelogenous leukemia in 2, and rare malignant disease in others. Four patients with osteosarcoma developed disease within the radiation field. Osteosarcoma was the most frequently occurring secondary neoplasm. Less toxic treatment modalities should be used to decrease the risk of secondary malignant diseases.

Deregulation of homologous recombination DNA repair in alkylating agent-treated stem cell clones: a possible role in the aetiology of chemotherapy-induced leukaemia

Chemotherapeutic regimes involving alkylating agents, such as methylators and crosslinking nitrogen mustards, represent a major risk factor for acute myeloid leukaemia. A high frequency of microsatellite instability and evidence of MSH2 loss in alkylating chemotherapy-related acute myeloid leukaemia (t-AML) suggests that DNA mismatch repair (MMR) dysfunction may be an initiating event in disease evolution. Subsequent accumulation of secondary genetic changes as a result of DNA MMR loss may ultimately lead to the gross chromosomal abnormalities seen in t-AML. Homologous recombination repair (HRR) maintains chromosomal stability by the repair of DNA double-strand breaks, and is therefore a possible target for deregulation in MMR dysfunctional t-AML. In order to test this hypothesis Msh2- proficient and -deficient murine embryonic stem (ES) cells were used to examine the effects of MMR status and methylating agent treatment on cellular expression of DNA double-strand break repair genes. HRR gene expression was significantly deregulated in Msh2 null ES cell clones compared to wild-type clones. Furthermore, some Msh2 null clones expressed high levels of Rad51 specifically, a critical component of HRR. Such Rad51 superexpressing clones were also observed when expression was determined in monocytic myeloid cells differentiated from ES cells. A deregulated HRR phenotype could be partially recapitulated in MMR-competent wild-type cells by treatment with the methylating agent, N-methyl-N-nitrosourea. Furthermore, treatment with melphalan, a leukaemogenic DNA crosslinking chemotherapy nitrogen mustard predicted to elicit HRR, selected against cells with deregulated HRR. These data suggest a t-AML mechanism whereby DNA MMR loss promotes the emergence of HRR gene superexpressing clones, with concomitant chromosomal instability. However, melphalan selection against clones with deregulated HRR suggests that persistence and expansion of unstable clones may require additional genetic alterations that promote cell survival.

Treatment-related myelodysplastic syndrome/acute myeloid leukemia in survivors of childhood cancer--an update

Treatment-related myelodysplastic syndrome/acute myeloid leukemia (t-MDS/t-AML) is a devastating complication of treatment for childhood cancer. However, the major cause of premature death of children treated for cancer remains their primary cancer. The understanding of the presentation, incidence, predisposing risk factors and pathobiology of t-MDS/t-AML is increasing. This increased understanding has not yet been translated into improved outcomes of therapy for t-MDS/t-AML. However, newer approaches are under study.

Second malignant neoplasms after treatment of childhood cancer

The aim of this study was to determine therapy-related risk factors for the development of second malignant neoplasm (SMN) after childhood cancer. The German Childhood Cancer Registry (GCCR) registers all childhood malignancies since 1980 including SMN. A nested case-control study with 238 SMN cases and 450 controls was conducted. A confirmatory, as well as an explorative, analysis was performed. Radiotherapy showed a small effect on the risk of SMN for doses >or=65 Gy. Regarding the chemotherapeutical agents, we saw increased Odds Ratios (OR) for high doses of cyclophosphamide (CP >8000 mg/m(2) OR=6.3 (95% Confidence Interval (CI): 1.3-30.2)), cisplatinum (DDP >435 mg/m(2) OR=2.8 (95% CI: 1.1-6.7)) and mercaptopurine (MP >5000 mg/m(2) OR=4.5 (95% CI: 1.1-18.9)). Patients jointly receiving high doses of MP (>5000 mg/m(2)) and dexamethasone (DEXA >or=1200 mg/m(2)) had an OR=6.9 (95% CI: 1.2-40.3). Our results could be added to those of other investigations to give indications for modifying future therapeutic strategies for childhood cancer.