M. Tubiana

Long-term results and prognostic factors in patients with differentiated thyroid carcinoma

A multivariate analysis of the prognostic factors was carried out on a series of 546 differentiated thyroid cancers followed for 8 to 40 years. For survival, the highest risk factor was associated with age; tumors diagnosed in patients younger than 45 years had higher relapse‐free survival (RFS) and total survival (TS) rates and a slower growth rate. In children, although the RFS and TS at 15 years were high, they decreased later. The second independent prognostic factor was histology. There was no difference between papillary and follicular well‐differentiated (FWD) tumors, but follicular moderately differentiated (FMD) had lower TS and RFS. Among FMD cancers, relapses occurred earlier and the interval between relapse and death was shorter. The third factor was sex. Tumors tended to disseminate more in male than in female patients. The survival rate after relapse was the same, however, suggesting that the growth rates are not different. The presence of palpable lymph nodes also had a significant independent impact on both TS and RFS. Patients treated after 1960 have a better outcome than patients treated earlier, although they did not differ in age distribution, histologic characteristics, sex ratio, or incidence of palpable lymph nodes. The distribution of time intervals between treatment and relapse was not compatible with an exponential failure time model but fit with a log‐logistic model. Relapses can occur as late as 30 years or more after initial treatment. Elevated levels of circulating thyroglobulin have been observed in about 12% of the patients who had been in complete remission for longer than 20 years.

The Linear No-Threshold Relationship Is Inconsistent with Radiation Biologic and Experimental Data

The carcinogenic risk induced by low doses of ionizing radiation is controversial. It cannot be assessed with epidemiologic methods alone because at low doses the data are imprecise and often conflicting. Since the 1970s, the radiation protection community has estimated the risk of low doses by means of extrapolation from the risk assessed at high doses, generally by using the linear no-threshold (LNT) model.

Long term risk of sarcoma following radiation treatment for breast cancer

Between 1954 and 1983, 7620 patients were treated for breast carcinoma at Institut Gustave Roussy (France). Of these patients, 6919 were followed for at least 1 year. Out of these, 11 presented with sarcomas thought to be induced by irradiation, 2 of which were Steward-Treves Syndrome, and 9 of which were sarcomas within the irradiated fields. All histological slides were reviewed and a comparison with those of breast cancer was done. The sites of these sarcomas were: parietal wall, 1 case; second costal cartilage, 1 case; infraclavicular region, 1 case; supraclavicular region, 2 cases; internal third of the clavicle, 2 cases; axillary region 2 cases; and the internal side of the upper arm (Stewart-Treves syndrome), 2 cases. The median age of these 11 patients at the diagnosis of sarcomas was 65.8 (49-83). The mean latent period was 9.5 years (4-24). Three patients underwent radical mastectomy and nine modified radical mastectomy. Only one patient received chemotherapy. The radiation doses received at the site of the sarcoma were 45 Gy/18 fr. for 10 cases and 90-100 Gy for 1 case (due to overlapping between two fields). The histology was as follows: malignant fibrous histiocytoma, 5 cases; fibrosarcoma, 3 cases; lymphangiosarcoma, 2 cases; and osteochondrosarcoma, 1 case. The median survival following diagnosis of sarcoma was 2.4 years (4 months-9 years). Two patients are still alive: one with recurrence of her breast cancer, the other in complete remission, with 7 and 3 years follow-up, respectively. All other patients died from their sarcomas. The cumulative incidence of sarcoma following irradiation of breast cancer was 0.2% (0.09-0.47) at 10 years. The standardized incidence ratio (SIR) of sarcoma (observed n# of cases (Obs)/expected n# of cases (Exp) computed from the Danish Cancer Registry for the same period) was 1.81 (CI 0.91-3.23). This is significantly higher than one, with a p = 0.03 (One Tailed Exact Test). The mean annual excess (Obs-Exp)/100.000 person-years at risk during the same period/(100,000) was 9.92. This study suggests that patients treated by radiation for breast cancer have a risk of subsequent sarcomas that is higher than the general population. However, the benefit from adjuvant radiation therapy in the treatment of breast cancer exceeds the risk of second cancer; therefore, the potential of radiation-induced sarcomas should not be a factor in the selection of treatment for patients with breast cancer.

Relation between the pathological nature and the growth rate of human tumors

Abstract An analysis of 530 cases reported in the literature over the past 14 years has demonstrated differences in the mean growth rate of various pathological types. This analysis shows that the various types of tumors may be ranked with respect to their increasing D.T.: embryonal carcinomas, lymphomas, malignant mesenchymal tumors, squamous cell carcinomas and adenocarcinomas.

Can we reduce the incidence of second primary malignancies occurring after radiotherapy? A critical review

Second primary malignancies (SPMs) occurring after oncological treatment have become a major concern during the past decade. Their incidence has long been underestimated because most patients had a short life expectancy after treatment or their follow-up was shorter than 15 years. With major improvement of long-term survival, longer follow-up, cancer registries and end-result programs, it was found that the cumulative incidence of SPM could be as high as 20% of patients treated by radiotherapy. This cumulative proportion varies with several factors, which ought to be studied more accurately. The delay between irradiation and solid tumor emergence is seldom shorter than 10 years and can be as long as half a century. Thus, inclusion in a cohort of patients with a short follow-up leads to an underestimation of the proportion of SPM caused by treatment, unless actuarial cumulative incidence is computed. The incidence varies with the tissue and organs, the age of the patient at treatment, hereditary factors, but also, and probably mainly, with dose distribution, size of the irradiated volume, dose, and dose-rate. An effort toward a reduction in their incidence is mandatory. Preliminary data suggest that SPMs are mainly observed in tissues having absorbed doses above 2 Gy (fractionated irradiation) and that their incidence increases with the dose. However, in children thyroid and breast cancers are observed following doses as low as 100 mGy, and in adults lung cancers have been reported for doses of 500 mGy, possibly due to interaction with tobacco. The dose distribution and the dose per fraction have a major impact. However, the preliminary data regarding these factors need confirmation. Dose-rates appear to be another important factor. Some data suggest that certain patients, who could be identified, have a high susceptibility to radiocancer induction. Efforts should be made to base SPM reduction on solid data and not on speculation or models built on debatable hypotheses regarding the dose-carcinogenic effect relationship. In parallel, radiation therapy philosophy must evolve, and the aim of treatment should be to deliver the minimal effective radiation therapy rather than the maximal tolerable dose.

External radiotherapy in thyroid cancers

Surgery is the most effective treatment for thyroid cancer; however, in some subsets of patients, the role of radiotherapy (RT) is important. The main indication for external‐beam RT is incomplete surgery. When neoplastic tissue is left behind at operation, RT must be considered, but only if an experienced surgeon feels that everything that can be done has been done. Generally, in those patients, the neoplastic tissue involves the larynx, trachea, esophagus, blood vessels or mediastinum. Of 539 patients with differentiated thyroid cancer treated at Villejuif, France, until 1976, 97 were treated by external radiotherapy after an incomplete surgical excision. Fifteen years after irradiation, the survival rate is 57% and is approximately 40% at 25 years. The relapse‐free survival is lower (39% at 15 years). In patients irradiated with an adequate dose (≥50 Gy) to residual neoplastic tissue after incomplete surgery, the incidence of local recurrence is low (actuarial probability of local recurrence 11% at 15 years versus 23% for patients treated by surgery alone, although the irradiated patients had larger and more extensive tumors). This demonstrates the efficacy of external‐beam radiotherapy. The effects of radiotherapy on a residual tumor can be monitored by a serum thyroglobulin assay. With regard to local control of tumors, the effectiveness of radioiodine administration is clearly lower. However, since radioiodine facilitates early detection of distant metastases, a combination of external RT and radioiodine is indicated and is well‐tolerated. For inoperable patients, the results of RT are limited: although complete remissions are sometimes obtained, the incidence of local recurrence is high. External RT is effective in medullary carcinoma despite the slow shrinkage of the tumor after irradiation. Assay of the calcitonin level helps to monitor the effects of the treatment during follow‐up and has demonstrated in some patients the efficacy of cervical RT. In undifferentiated cancers, the results of RT are poor. Combination of RT and chemotherapy are being explored despite the disappointing preliminary results of this combination.

Repair of potentially lethal radiation damage in vitro and in vivo.

The repair of potentially lethal damage was studied in plateauphase cultures of human LICH cells in vitro and in NCTC-2472 mouse fibrosarcoma grown in vivo in both the ascites and solid forms. Solid tumors and old, slowly-growing ascites tumors repaired potentially lethal damage; the kinetics and amount of repair were similar to those found in plateau-phase cultures. Repair in vitro was associated with a change in the slope of the survival curve without an accompanying increase in the shoulder of the curve. The effects of repair of sublethal and potentially lethal damage were additive. Thus this repair is another factor which influences the response of tumors to fractionated irradiation.

Cell proliferation kinetics in human solid tumors: relation to probability of metastatic dissemination and long-term survival

A large number of studies have investigated the relationship between the long-term survival and the percentage of tumor cells in S phase assessed by autoradiography after tritiated thymidine labelling, image cytometry, flow cytometry or labelling with an halogenated analog of thymidine, in various types of human solid tumors. The survey of the results clearly shows that the S-phase fraction (SPF) is of high prognostic significance in several types of cancers, in particular in breast cancers, non-Hodgkin lymphomas, ovarian cancers, neuroblastoma, bladder cancers and lung cancers. SPF was found of high independent significance in 10 of the 11 studies in which multivariate analyses of prognostic factors had been carried out. Proliferation appears generally to be of higher prognostic significance than ploidy. In view of the wide differences in the biological characteristics of the tumors studied, it is likely that the association between a high proliferation rate and the degree of tumor aggressiveness is a general feature of human solid tumors. However, high proliferative rate of tumor cells is probably not the cause of tumor biological aggressiveness but a variable associated with it. The extent to which cells escape from the regulatory systems which control their proliferation appears to be a good index of tumor progression.

Pericarditis and myocardial infarctions after Hodgkin's disease therapy

From 1971 to 1984, 499 patients with all stages of Hodgkins disease received mediastinal irradiation at the Institut Gustave-Roussy by 25 MV photons from a linear accelerator. Thirty-five pericarditis (10-year cumulative incidence rate of 9.5%) and 13 myocardial infarctions (MI) (10-year cumulative incidence rate of 3.9%) were observed. In contrast, no cases were diagnosed in a parallel series of 138 Hodgkins disease patients treated without mediastinal irradiation during the same period of time (p less than 0.005 for pericarditis, p less than 0.05 for MI). By multivariate analysis, the role of total radiation dose given to the mediastinum and that of fraction size were evaluated, adjusting for age, sex, mediastinal involvement, and type of chemotherapy. The pericarditis risk was significantly increased with total dose greater than or equal to 41 Gy (relative risk (RR) = 3.25, p = 0.006) and with dose per fraction greater than or equal to 3.0 Gy (RR = 2.0, p = 0.06). The myocardial infarction risk was not found to be related to total dose nor to fraction size in this series, possibly because of the small number of events.

Kinetic parameters and the course of the disease in breast cancer

The correlation between the labeling index (LI) of the primary mammary tumor and the course of the disease after initial treatment was studied prospectively on 128 patients. The surgical specimens of breast tumors were incubated in vitro with tritiated thymidine and autoradiographies were performed. Patients were treated by a simple mastectomy and axillary lymph nodes dissection; patients in whom one or more lymph nodes were found to be involved received postoperative radiotherapy. None of the patients received adjuvant chemotherapy. As the LIs were not known at the time of treatment, their values did not influence the choice of therapy. The follow‐up period is greater than six years for all patients. The higher the LI, the shorter were the time intervals from initial treatment to first relapse or from first relapse to death. Moreover, significant correlations were found between the LI and the relapse‐free survival and the survival rates. The proportion of relapses was particularly small in the group with the low LI. The shape of the curve suggests that the outcome in this group will be better than that in the group with a high or a median LI.