Strategies and methodologies for identifying molecular targets in sarcomas and other tumors

Prognostic significance of STAT3 and phosphorylated STAT3 in human soft tissue tumors - a clinicopathological analysis

Background

Signal transducer and activator of transcription 3 (STAT3) is a key signaling molecule and a central cytoplasmic transcription factor, implicated in the regulation of growth. Its aberrant activation has been demonstrated to correlate with many types of human malignancy. However, whether constitutive STAT3 signaling plays a key role in the survival and growth of soft-tissue tumors is still unclear and hence needs to be elucidated further. In our study we examined the expression levels of STAT3 and pSTAT3 in different grades of soft tissue tumors and correlated with its clinicopathological characteristics.

Methods

Expression levels of STAT3 and pSTAT3 in soft tissue tumors were studied using Immunohistochemistry, Western blotting and Reverse transcriptase- PCR and correlated with its clinicopathological characteristics using Chi squared or Fisher's exact test and by logistic regression analysis. Statistical analysis was done using Intercooled Stata software (Intercooled Stata 8.2 version).

Results

Of the 82 soft tissue tumor samples, fifty four (65.8%) showed immunoreactivity for STAT3 and twenty eight (34.1%) for pSTAT3. Expression of STAT3 and pSTAT3 was significantly associated with tumor grade (P < 0.001; P < 0.001), tumor location (P = 0.025; P = 0.027), plane of tumor (P = 0.011; P = 0.006), and tumor necrosis (P = 0.001; P = 0.002). Western blotting and RT-PCR analysis showed increased expression of STAT3 and p-STAT3 as grade of malignancy increased.

Conclusion

These findings suggest that constitutive activation of STAT3 is an important factor related to carcinogenesis of human soft tissue tumors and is significantly associated with its clinicopathological parameters which may possibly have potential diagnostic implications.

Topoisomerase II-alpha protein expression and histological response following doxorubicin-based induction chemotherapy predict survival of locally advanced soft tissues sarcomas

PURPOSE

Neoadjuvant chemotherapy for locally advanced soft tissue sarcomas (LASTS), although not standard, represents a promising option for resectable tumours. Current lack of biological predictors of chemotherapy response led us to establish a relationship between Topoisomerase II-alpha (Topo2A), HER2, excision repair cross-complementing group 1 (ERCC1) protein expression, histological response and clinical outcomes of LASTS patients.

PATIENTS AND METHODS

A retrospective study based on clinical data and archival paraffin-embedded tumour tissue at diagnosis from 78 consecutive LASTS patients treated with neo-adjuvant chemotherapy in our institution enabled analysis of ERCC1, HER2 and Topo2A protein expression by immuno-histochemistry.

RESULTS

Disease free survival (DFS) and overall survival (OS) were 48% and 64%, respectively. The annual risk of relapse increased with a higher percentage of residual identifiable cells (RIC). A higher Topo2A protein was associated with an improved rate of good HR (r=0.416) and with a decreased risk of relapse. Median DFS decreased with low Topo2A (p⩽0.042). The ERCC1 status had no impact on histological response while ERCC1 positive tumours correlated with a favourable OS (p ≤ 0.058). Patients with LASTS co-expressing Topo2A and ERCC1 had a significant better outcome (p=0.018). Topo2A was the only independent variable linked to a good HR (p ≤ 0.017); histological grade 3 was the only independent adverse prognostic variable linked to both DFS (p ≤ 0.04) and OS (p ≤ 0.004).

CONCLUSIONS

While histological response predicts better DFS, Topo2A protein expression correlates with histological response and better DFS. The combination of an early predictive factor for chemosensitivity (Topo2A) and for survival (ERCC1) highlights the possibility to develop individualised therapeutic approaches (CONTICANET program).

The role of radiation in retroperitoneal sarcomas: a surgical perspective

PURPOSE OF REVIEW

This review focuses on the current concepts relating to the use of radiation therapy in the care of surgical patients with retroperitoneal sarcoma. Radiation therapy for retroperitoneal sarcoma patients is complex because it requires decisions on not only the timing of administration, but also the technique of delivery.

RECENT STUDIES

Multiple studies have reported improved local recurrence-free survival in patients who received adjuvant external beam radiation therapy. Recent studies have demonstrated the efficacy of more sophisticated delivery methods for radiation therapy to deliver high dose rates while sparing surrounding normal tissues. Other recent studies have demonstrated the safety and feasibility of preoperative radiation therapy for retroperitoneal sarcoma. Preoperative radiation results in decreased local recurrence rates and minimal toxicity. The use of intraoperative radiation therapy has also been examined as a means to improve local recurrence rates, but may be associated with more radiation-related morbidity.

SUMMARY

There is good evidence that radiation therapy improves local control rates. Preoperative external beam radiation therapy may be the preferred sequence to improve tumor resectability and local-regional control with less risk of complications. Although data suggest that the addition of intraoperative radiation therapy to external beam radiation therapy improves local control, intraoperative radiation therapy may be related to additional toxicity.