Anaplastic thyroid carcinoma: a therapeutic challenge

Anaplastic thyroid cancer

Anaplastic thyroid carcinoma is one of the most aggressive malignancies, with a poor prognosis. Although rare, representing only 2% of clinically recognized thyroid cancers, the overall median survival is limited to months. Most patients are elderly and seek treatment with a rapidly growing mass. Almost half the patients seek treatment with distant metastases, with as many as 75% developing distant disease during their illness. In most the patients, complete surgical resection is not possible. There are, however, a few patients with resectable disease reported in the literature who have demonstrated long-term survival with aggressive multimodal therapy that included surgery, radiation, and chemotherapy. Preclinical studies in human anaplastic thyroid carcinoma cell lines show promise that new approaches to the management of this disease will be found in the future. Until such time when an effective regimen is found, all patients with anaplastic thyroid carcinoma should be evaluated for multimodal therapy in the setting of a clinical trial.

ONYX-015, an E1B gene-defective adenovirus, induces cell death in human anaplastic thyroid carcinoma cell lines

Being one of the most lethal human neoplasms and refractory to such conventional treatment as chemo- and radiotherapy, anaplastic thyroid carcinoma is a prime target for innovative therapy. p53 gene inactivation is a constant feature of this neoplasia. Therefore, we evaluated a therapeutic approach based on an E1B 55-kDa gene-defective adenovirus (ONYX-015) that replicates only in cells with impaired p53 function and leads to cell death. Here we report that the ONYX-015 virus induces cell death in three human thyroid anaplastic carcinoma cell lines (ARO, FRO, and KAT-4). In addition, we found that the growth of xenograft tumors induced in athymic mice by the injection of ARO cells was drastically reduced by ONYX-015 treatment. The ONYX-015 virus worked synergistically with two antineoplastic drugs (doxorubicin and paclitaxel) in inducing ARO and KAT-4 cell death. These results suggest that ONYX-015 may be a valid tool in the treatment of the human thyroid anaplastic carcinoma.

The effect of surgery and radiotherapy on outcome of anaplastic thyroid carcinoma

BACKGROUND

Anaplastic thyroid carcinoma (ATC) is an aggressive rare tumor. We analyzed our experience for prognosis and the effect of surgery and radiotherapy on patients with ATC.

METHODS

We conducted a retrospective review of all patients (n = 67) with ATC treated at a tertiary care center from 1969 to 1999. Survivor median follow-up was 51 months. Tumor and patient characteristics and therapy were assessed for effect on survival by multivariate analysis.

RESULTS

Patients presented with a neck mass (99%), change of voice (51%), dysphagia (33%), and dyspnea (28%). Surgery was performed in 44 of 67 patients, with 12 complete resections. The 6-month and 1- and 3-year survival rates were 92%, 92%, and 83% after complete resection; 53%, 35%, and 0% after debulking; and 22%, 4%, and 0% after no resection, respectively (P < .0001). A radiation dose of >45 Gy improved survival as compared with a lower dose (P = .02). Multivariate analysis showed that age < or = 70 years, absence of dyspnea or dysphagia at presentation, a tumor size < or = 5 cm, and any surgical resection improved survival (P < .05).

CONCLUSIONS

Candidates for surgery with curative intent for ATC are patients < or = 70 years, tumors < or = 5 cm, and no distant disease. Radiotherapy >45 Gy improves outcome.

Anaplastic thyroid carcinoma: a 50-year experience at a single institution

BACKGROUND

Anaplastic thyroid carcinoma (ATC) is among the most aggressive of human malignancies. However, there have been few large studies of histologically well-defined ATC. We report the results of a 50-year experience of this lethal malignancy.

METHODS

We reviewed all cases of ATC managed in this institution between 1949 and 1999. One pathologist (J.R.G.) reviewed all pathologic material. Clinical details were obtained from medical records, and current status of all patients was determined.

RESULTS

There were 134 cases, with a female-to-male ratio of 1.5:1 and a mean age of 67 years. Benign thyroid disease was present in 27 cases (20%) and well-differentiated thyroid carcinoma in 31 (23%). Sixty-two patients (46%) had distant metastases at diagnosis, and 98% of the tumors were locally invasive. Primary treatment was surgical for 96 patients (72%). Complete resection was achieved in 29 cases (30%), with "minimal residual disease" in 25. Neither extent of operation nor completeness of resection affected survival (P > .4). Postoperative radiotherapy gave slightly longer median survival (5 vs 3 months), which was not significant (P < .08). Multimodal therapy, including operation, chemotherapy, and radiotherapy, did not improve survival.

CONCLUSIONS

The outlook for patients with ATC remains grim. Novel treatments for ATC are desperately needed.

Effect of primary treatment on survival in anaplastic thyroid carcinoma

AIMS

Anaplastic thyroid carcinoma (ATC) is a fatal disease despite combined treatment consisting of chemotherapy, radiotherapy and surgery. The optimal sequence of treatment modalities is not known. The purpose of our retrospective non-randomized study was to find out whether timing of the treatment modality had any influence on survival, and to find out if primary surgery prolongs survival in comparison to primary chemotherapy and/or radiotherapy.

METHODS

From our database of 162 patients with ATC treated at the Institute of Oncology Ljubljana from 1972-98, 79 patients (26 men, 53 women; age: 40-86 years, mean age 65 years) were included in this retrospective study. The 83 patients with distant metastases on admission, with the survival shorter than one month or patients without any treatment were excluded. The 79 patients were classified into (1) primary surgery group (n=26) and (2) primary chemotherapy and/or radiotherapy group (n=53), including the 12 patients in whom surgery was performed after chemotherapy and/or radiotherapy. The survival of both groups was compared by log-rank test and group characteristics by ANOVA and(2 test using SPSS program.

RESULTS

In comparison to the primary surgery group, the patients from the primary chemotherapy and/or radiotherapy group were older and had faster growing, and larger tumours, which were not confined to the thyroid, and more frequently had regional metastases. There was no difference in the survival of the two groups (P=0.17). Survival for longer than one year was observed in 25% of patients with primary surgery and in 21% of patients with primary chemotherapy and/or radiotherapy. The best results (50% survival at one year) were obtained in patients in whom the tumour was surgically removed after primary chemotherapy and radiotherapy.

CONCLUSION

This study suggests that the timing of the treatment modalities has an impact on survival and that treatment should start with chemotherapy and/or radiotherapy, with surgery to follow if possible.)

Thyroid cancer

Four types of thyroid cancer comprise more than 98% of all thyroid malignancies. Papillary thyroid carcinoma (PTC) may have a very benign course while undifferentiated thyroid carcinoma (UTC) belongs to the most aggressive human malignancies. A variety of genes have been identified to be involved in the pathogenesis of thyroid carcinoma. Somatic Ras mutations seem to be an early event and are frequently found in follicular thyroid carcinomas. Somatic rearrangements of RET and TRK are almost exclusively found in PTC and may be found in early stages. Germline RET missense mutations lead to hereditary medullary thyroid carcinoma (MTC). In contrast, the significance of somatic RET mutations in sporadic MTC is unknown. p53 seems to play a crucial role in the dedifferentiation process of thyroid carcinoma. The precise role of PTEN remains to be elucidated. The only clearly identified exogenous factor that may lead to thyroid carcinoma (mainly PTC) is radiation. Of interest, radiation is capable to induce RET rearrangements. In general, early diagnosis is mandatory to enable the chance of cure. Surgery is the treatment of choice. Depending on the tumour type, surgery in combination with either radioiodine, external radiation or chemotherapy often enables the control of local tumour burden. In MTC and UTC, once thyroid cancer is spread to distant organs, efficacious therapeutic agents are almost non-existing. However, our growing knowledge of genes involved in thyroidal oncogenesis may contribute to the development of more effective treatment modalities. Some preliminary data on gene therapy are quite promising.

Cytotoxic activity of 2',2'-difluorodeoxycytidine (gemcitabine) in poorly differentiated thyroid carcinoma cells

Poorly differentiated and anaplastic thyroid cancers are aggressive and usually fatal neoplasms, despite aggressive treatment. We performed an in vitro study to assess the activity of gemcitabine (2',2' difluorodeoxycytidine), a new fluorinated nucleoside analogue, against three poorly differentiated human thyroid carcinoma cell lines (ARO, WRO, and NPA). Each cell line was exposed to increasing concentrations of gemcitabine (0.0003 to 3000 mumol/L) for 24, 48, and 72 hours. Maximal reduction in cell viability was seen after 72 hours of gemcitabine for all three cell lines as measured by 3-(4,5-dimethyl thiazolyl-2)-2,5-diphenyl tetrazolium bromide (MTT) assay. NPA cells were more sensitive than the other two lines after 24 and 48 hours of exposure, but all cell lines were similarly sensitive at 72 hours. A cytotoxic effect was confirmed by DNA assay of adherent cells. IC50 concentrations for reduction in cell viability ranged from 0.731 and 0.986 mumol/L for each cell line after 72 hours of exposure. These concentrations are lower than serum levels in phase 1 clinical trials of gemcitabine for other malignancies. In summary, gemcitabine has activity against poorly differentiated thyroid cancer cell lines in vitro. In vivo studies using xenograft models are warranted to confirm these promising observations.