Do rare cancers deserve specific strategies for cancer research?

Challenges and opportunities for sarcoma care and research in Latin America: a position paper from the LACOG sarcoma group

As a developing region, Latin America faces unique cancer control and prevention challenges, which are intensified when considering rare cancers, including sarcomas. Sarcomas are a group of malignancies that arise in the connective tissues of the body-such as muscle, fat, nerves, blood vessels, and bones-accounting for a diverse range of tumours that, although rare, require specialized attention. Sarcoma care and research in Latin America require a comprehensive approach that includes deeper epidemiologic knowledge, diagnostic capacity building, access to innovative treatments, increased patient advocacy, and strengthening of clinical research capacity. This article will review current challenges and opportunities for treating patients with sarcoma in Latin America and outline a pathway toward improvement for regional collaborative groups.

Treatment challenges in and outside a network setting: Soft tissue sarcomas

Patients with soft tissue sarcoma (STS) experienced better outcomes when treated according to existing clinical practice guidelines either at reference institution or dedicated treatment networks. Despite increasing evidence supporting referral to sarcoma specialised units, up to half of patients are not managed according to guidelines, particularly those in the early stage of their disease requiring surgery. Also, criteria to certify expertise of institutions, such as the treatment volume, are debated and health authorities have only recently started identification of these centres and creation of treatment networks in Europe as well as in several countries. This process have important implications for both patient outcomes and innovation of existing treatment strategies through clinical research, making improvement of clinical pathways a priority for health care authorities. This article will discuss issues with management of patients with STS, such as pathological diagnosis and adherence to guidelines, and the definition of referral centres and networks will be illustrated along with existing experiences and population-based data.

Research methods to change clinical practice for patients with rare cancers

Rare cancers are a growing group as a result of reclassification of common cancers by molecular markers. There is therefore an increasing need to identify methods to assess interventions that are sufficiently robust to potentially affect clinical practice in this setting. Methods advocated for clinical trials in rare diseases are not necessarily applicable in rare cancers. This Series paper describes research methods that are relevant for rare cancers in relation to the range of incidence levels. Strategies that maximise recruitment, minimise sample size, or maximise the usefulness of the evidence could enable the application of conventional clinical trial design to rare cancer populations. Alternative designs that address specific challenges for rare cancers with the aim of potentially changing clinical practice include Bayesian designs, uncontrolled n-of-1 trials, and umbrella and basket trials. Pragmatic solutions must be sought to enable some level of evidence-based health care for patients with rare cancers.

Clinical application of molecular pathology in sarcomas

PURPOSE OF REVIEW

This review is intended to highlight the clinical application of molecular pathology as a tool for diagnostic accuracy and prognostic and predictive use and finally to discover novel molecular therapeutic targets.

RECENT FINDINGS

We are living an exciting era in sarcomas' therapy. This is the result of overcoming two crucial obstacles: lack of effective and specific drugs; lack of specific therapeutic regimen for distinct clinical entities. As new specific drugs have become available, it has become clear that an accurate diagnosis is the prerequisite for a specific therapy. This approach has been successfully applied to gastrointestinal stromal tumor and is now also being used in other sarcomas. The more recent findings are hereby reviewed.

SUMMARY

The inclusion of the molecular pathology in the diagnostic surgical pathology is instrumental for the application of molecularly tailored therapy. However, the degree of complexity of this approach requires additional caution in the data interpretation and in the reproducibility of the results. As molecular knowledge is improving and more sophisticated and powerful techniques are going to be routinely used, the success rate in treating sarcomas is expected to significantly increase.

Sunitinib in advanced alveolar soft part sarcoma: evidence of a direct antitumor effect

BACKGROUND

The purpose of this study was to confirm sunitinib activity in alveolar soft part sarcoma (ASPS) and to report on new insights into the molecular bases thereof.

PATIENTS AND METHODS

From July 2007, nine patients with progressive metastatic ASPS received sunitinib 37.5 mg/day, within a named use program. Cryopreserved material was available for five naive patients, among whom three received sunitinib. Immunofluorescence (IF)/confocal microscopy, biochemical, and molecular/cytogenetic analyses were carried out, complemented by antiproliferative and activation assays in a short-term culture derived from one case.

RESULTS

All patients were eligible for response. Best RECIST response was partial response in five cases, stable disease in three, and progression in one. The median progression-free survival was 17 months. Positron emission tomography results were consistent. Two cases of interval progressions were recorded. Antiproliferative assays and biochemistry on short-term culture showed that sunitinib is able to markedly impair ASPS cells growth and switch-off PDGFRB. IF/confocal microscopy demonstrated coexpression and physical association between PDGFRB/vascular endothelial growth factor receptor 2 (VEGFR2) and RET/VEGFR2 in ASPS cells, which was validated by biochemistry. PDGFRB, RET, and MET ligand-dependent activation was confirmed.

CONCLUSIONS

We confirm the clinical efficacy of sunitinib in ASPS, mediated by PDGFRB, VEGFR2, and RET, which are all expressed in tumor cells. A direct antitumor effect was shown in a short-term cell culture.