Multiple primary malignancies in osteosarcoma patients. Incidence and predictive value of osteosarcoma subtype for cancer syndromes related with osteosarcoma

Multilocus inheritance determines predisposition to α-radiation induced bone tumourigenesis in mice

In a recent study, we presented evidence for genetic predisposition governing radiation osteosarcomagenesis in mice. Following the incorporation of the bone-seeking alpha emitter 227Th, approximately 25% of the variance in osteosarcoma incidence was determined by inherited genetic factors. We have now mapped 5 susceptibility loci in crosses between the more susceptible BALB/c and the more resistant CBA/Ca strains. The major QTL on chromosome 14 overlaps with a locus that was already found in our previous study, using different strains of mice. Here, we investigate the effect by which the major susceptibility locus and 4 minor modifier loci interact to influence osteosarcoma predisposition. Following incorporation of the bone-seeking isotope, 100% of mice that harbour high-risk genotypes at all 5 susceptibility loci develop osteosarcoma with an average of 472 days latency times. In 10 mice inheriting exclusively low-risk genotypes only 1 osteosarcoma was found, arising after 733 days latency time. Inheritance of distinct combinations of BALB/c and CBA/Ca alleles at the susceptibility loci confer more extreme phenotypes in terms of susceptibility or resistance than observed in either of the two parental inbred strains. From the present study, we demonstrate that additive effects of multiple alleles, each making only a minor phenotypic contribution, can combine and significantly alter tumour risk. This mechanism can be of particular importance in genetically heterogeneous populations such as man.

Alpha-tocopheryl succinate alters cell cycle distribution sensitising human osteosarcoma cells to methotrexate-induced apoptosis

alpha-Tocopheryl succinate (alpha-TOS) exerts pleiotrophic responses in malignant cells leading to cell cycle arrest, differentiation and apoptosis. We tested the ability of alpha-TOS to induce apoptosis or cell cycle perturbation in three human osteosarcoma (OS) cell lines which differ in their pRB and p53 status. We found high levels of apoptosis in OS cells carrying wild-type p53 gene when exposed to alpha-TOS, while the mutant p53 cells were resistant. A S/G2 transition arrest was observed in two OS cell lines exposed to alpha-TOS, which sensitised them to methotrexate, an agent whose activity is cell cycle-dependent. We propose that alpha-TOS may be used as a drug or an adjuvant for treatment of osteosarcomas.

Clinico-histologic parameters of osteosarcoma patients with late relapse

Primary high-grade intramedullary osteosarcoma of the extremities is a clinically aggressive bone tumour. There is an ongoing effort to further improve efficacy of neo-adjuvant chemotherapy and reduce chemotoxicity by trying to identify osteosarcoma patients who are at risk of treatment failure as well as to identify those who can do with less chemotherapy. In only 5% of patients, first distant metastasis or local relapse occurs 5 years or more after initial treatment for osteosarcoma. Patients and physicians can therefore easily erroneously consider a patient with osteosarcoma cured if he or she is disease-free for more than 5 years following diagnosis and treatment. To investigate if these rare late relapsing patients are characterised by specific clinico-pathological features, we examined clinical and histological variables of late relapse (first local recurrence or metastasis 5 years or more after initial diagnosis) out of a total of 2,243 patients, with a special interest in the histological osteosarcoma subtype. In total, 33 patients had a documented relapse 5 years or more after diagnosis. Half of the patients had good response (>or=90% necrosis) to pre-operative chemotherapy and the other half a poor response (<90% necrosis) and late relapses seemed to be more frequently proportionately in those who had a good initial response to chemotherapy. The occurrence of late relapse did not appear to be associated with age or gender. Although not statistically significant, there was a trend for patients with a chondroblastic subtype of osteosarcoma, or a location in the tibia or fibula, to have a higher risk for late relapse.