Biomarkers in childhood non-Hodgkin's lymphomas

Pediatric non-Hodgkin's lymphomas (NHLs) are a heterogeneous group of malignancies with distinct clinical, pathological, immunological and genetic characteristics. More than 90% of pediatric NHLs belong to one of three major histological subtypes: mature B-cell neoplasms, lymphoblastic lymphomas and anaplastic large-cell lymphomas. The recognition that different subtypes require different treatment regimens resulted in therapeutic strategies leading to over 80% of patients being cured. On the other hand, patients with resistant or relapsed disease have a poor prognosis. Prognostic biomarkers have not yet been identified for all pediatric NHLs and, although some are very important for diagnosis and prognosis, others may be of questionable value. Discovery of new biomarkers suitable for clinical application may aid the diagnosis and classification of lymphomas, which should, in turn, lead to better patient stratification. Consequent development of new treatment and follow-up approaches should lead to more efficient and less toxic treatment in children with NHL.

Where do selective estrogen receptor modulators (SERMs) and aromatase inhibitors (AIs) now fit into breast cancer treatment algorithms?

The agents used for endocrine therapy in patients with breast cancer have changed markedly over the past decade. Tamoxifen remains the anti-oestrogen of choice, but could be replaced by the oestrogen receptor down-regulator ICI 182780 or by the fixed ring triphenylethylene arzoxifene (previously SERM III) soon. Whilst aminoglutethimide and 4-OH androstenedione were the aromatase inhibitors of choice, they have been replaced by non-steroidal (anastrozole and letrozole) and steroidal (exemestane) inhibitors of high potency and low side effect profile. Previously, often used treatments such as progestogens (megestrol acetate and medroxyprogesterone acetate) and androgens are now rarely used or confined to fourth or fifth line treatments. The LHRH agonist, goserelin, remains the treatment of choice for pre-menopausal patients with advanced breast cancer although recent randomised trials indicate a response, time to progression and survival advantage for the combination of goserelin and tamoxifen compared with goserelin alone. The newer treatments have led to questions concerning the optimum sequence of agents to use in advanced breast cancer and as neo-adjuvant and adjuvant therapy in relation to surgery. Two trials of anastrozole compared with tamoxifen and one trial of letrozole compared with tamoxifen indicate that the new triazole aromatase inhibitors have a significant advantage over the anti-oestrogen with respect to time to progression and survival. Similarly, triazole aromatase inhibitors give faster and more complete responses compared with tamoxifen when used in post-menopausal women before surgery. Major research questions remain with respect to the aromatase inhibitors used as adjuvant therapy. Anastrozole is being tested alone or in combination with tamoxifen compared with tamoxifen in the 'so-called' ATAC trial. Over 9000 patients have been randomised to this important study: the results will be available late-2001. A similar study comparing letrozole and tamoxifen started recently under the auspices of the Breast International Group. Importantly, this trial is also comparing the sequence of tamoxifen followed by letrozole (or vice versa). A similar trial of exemestane given after 2-3 years of tamoxifen compared with 5 years of tamoxifen is recruiting well as is a study comparing letrozole (or placebo) for 5 years after 5 years of adjuvant tamoxifen. These studies may show that aromatase inhibitors are superior to tamoxifen or that a sequence is preferable.ICI 182780 causes complete oestrogen receptor down-regulation leading to a the lack of agonist activity of the drug. Two trials of ICI 182780 compared with anastrozole for advanced disease will report later this year and a comparison with tamoxifen next year. Arzoxifene (SERM III) is being tested against tamoxifen. These studies are likely to result in new anti-oestrogens being introduced into the clinic. Most of our endocrine treatments deprived the tumour cell of oestradiol. In vitro experiments with MCF-7 cells indicate that tumour cells can adapt and then grow in response to low oestrogen concentrations in the tissue--culture medium. Importantly, the cells were shown to apoptose in response to high oestrogen concentrations. A recent clinical trial has demonstrated a high response rate to stilboestrol given after a median of four previous oestrogen depriving endocrine therapies. These data and the newer treatments available indicate a need to re-think our general approach to endocrine therapy and endocrine prevention.

Diffuse large cell lymphoma

A review of new or emerging ideas concerning diffuse large B-cell lymphomas is presented, with particular emphasis on histologic classification, genetic prognostic factors, first-line and salvage treatments, and specific locations such as neurologic, cutaneous, or gastrointestinal sites. This lymphoma remains the most heterogeneous of all lymphomas for its clinical characteristics and outcome. This heterogeneity is probably secondary to the fact that a large proportion of lymphomas seems to occur from a transformation of an unknown indolent lymphoma.