Salivary gland tumors in atomic bomb survivors, Hiroshima, Japan. I. Epidemiologic observations

LNT and cancer risk assessment: Its flawed foundations part 1: Radiation and leukemia: Where LNT began

This paper evaluates the scientific basis for the adoption of the linear non-threshold (LNT) dose response model for radiation-induced leukemia. This LNT risk assessment application for leukemia is significant because it: (1) was generalized for all tumor types induced by ionizing radiation and chemical carcinogens at relatively high doses and; (2) it was based on the mechanistic assumption of low dose linearity for somatic cell mutations as determined from responses in mature spermatozoa of fruit flies. A serious problem with the latter assumption is that those spermatozoa lack DNA repair. The acceptance of the LNT dose response model for cancer risk assessment was based on the convergence of recommendations of the BEAR I Genetics Panel (1956a) for reproductive cell gene mutations and those of Lewis (1957a) for somatic cell mutation and its capacity to explain apparent and/or predicted linear dose responses of ionizing radiation-induced leukemia in multiple and diverse epidemiological investigations. Use of that model and related dose response beliefs achieved rapid, widespread and enduring acceptance in the scientific and regulatory communities. They provide the key historical foundation for the sustained LNT-based policy for cancer risk assessment to the present. While previous papers in this series have challenged key scientific assessments and ethical foundations of the BEAR I Genetics Panel, the present paper provides evidence that Lewis: 1) incorrectly interpreted the fundamental scientific studies used to support the LNT conclusion even though such studies show consistent hormetic-J-shaped dose response relationships for leukemia in Hiroshima and Nagasaki survivors; and, 2) demonstrated widespread bias in support of an LNT conclusion and related policies, which kept him from making an objective and fair assessment. The LNT recommendation appears to have been uncritically accepted and integrated into scientific and regulatory practice in large part because it inappropriately appealed to existing authority and it garnered the support of those who were willing to risk greatly exaggerating the public's fears of environmentally-induced disease, such as enhanced risk of leukemia, with the goal of stopping the atmospheric testing of atomic bombs. Adoption of the LNT recommendation demonstrated extensive penetration of ideological influence affecting governmental, scientific and regulatory evaluation at the highest levels in the United States. This paper demonstrates that the scientific foundations for cancer risk assessment were inappropriately and inaccurately assessed, unethically adopted and require significant historical, scientific and regulatory remediation.

Characteristics of 5015 Salivary Gland Neoplasms Registered in the Hiroshima Tumor Tissue Registry over a Period of 39 Years

Salivary gland neoplasms are uncommon, and their epidemiology in Japan has not been well described. We conducted a retrospective review of salivary gland tumors registered in the Hiroshima Tumor Tissue Registry over a period of 39 years. The subjects were 5015 cases ranging in age from 6 to 97 (mean, 54.3) years old. The incidence of both benign tumors and malignant tumors increased with age until 60-69 years and then declined. Among the 5015 salivary gland neoplasms, 3998 (80%) were benign and 1017 (20%) were malignant. Pleomorphic adenoma (PA) was the most frequent benign tumor (68%), followed by Warthin tumor (26%). Adenoid cystic carcinoma (ACC) (27%) and mucoepidermoid carcinoma (MEC) (26%) were the two most frequent malignant tumors. Characteristically, there was a very low incidence of polymorphous adenocarcinoma in Japan. The average annual age-adjusted incidence rate per 100,000 population was 3.3 for benign tumors and 0.8 for malignant tumors. This is the large-scale multi-institutional analysis to describe the characteristics of salivary gland neoplasms, based on the pathological tissue registry data. We hope that the present data can contribute to early diagnosis and effective treatment of salivary gland tumors and to cancer prevention.

AHNS series: Do you know your guidelines? Diagnosis and management of salivary gland tumors

This article is the next installment of the series "Do you know your guidelines" presented by the Education Committee of the American Head and Neck Society. Guidelines for the workup and management of tumors of the major and minor salivary glands are reviewed.

Salivary gland malignancies in children

With an annual incidence of less than 1 per million, salivary gland malignancies in children are rare, constituting less than 10% of pediatric head and neck cancer. Although over 20 histologic types of salivary gland cancer have been reported in adults, a smaller number have been observed in the pediatric population. Mucoepidermoid carcinoma is the most common histologic type, followed by acinic cell carcinoma. Since the majority of salivary gland carcinomas are diagnosed at an early stage, the overall prognosis is often favorable with complete surgical resection. To date, no prospective or retrospective data comparing outcomes of surgery alone versus multimodality therapy in the management of salivary gland malignancies in the pediatric population exists. Consequently, management decisions are made on a case-by-base basis, taking prognosis, treatment-related morbidity, and long-term sequelae into account.

Multiple malignant salivary gland neoplasms: mucoepidermoid carcinoma of palate and adenoid cystic carcinoma of floor of mouth

Salivary gland tumors usually occur as single lesions. To have more than one tumor is unusual. We report a case of an adult male who presented with a mucoepidermoid carcinoma involving the minor salivary glands of the palate at age 57 years, followed by an adenoid cystic carcinoma of the floor of mouth at age 63 years. The patient later succumbed to non-Hodgkin lymphoma at age 72 years. There are 31 acceptable cases of multiple malignant salivary gland neoplasms reported in the world literature. Multiple malignant tumors of the same histologic type are more common than those of different histologic type. Bilateral acinic cell adenocarcinoma was the most frequent combination of multiple salivary gland malignancy, accounting for 14 cases (10 synchronous and four metachronous). All involved the parotid glands bilaterally with the exception of one case that involved parotid and submandibular gland. Polymorphous low-grade adenocarcinoma accounted for three of the four cases of multiple malignant tumors involving minor salivary glands. Individuals with a history of malignancy are at risk for the development of additional malignant tumors and should receive appropriate clinical follow-up.

Occupational Exposures and Salivary Gland Cancer Mortality Among African American and White Workers in the United States

We conducted a large death certificate-based case-control study to assess occupational risks for salivary gland cancer. African American (168 cases, 672 controls) and white (2237 cases, 8748 controls) cases from 24 states (1984-1989) were matched to controls by age, sex, race, and region. Race- and sex-stratified multiple logistic regression models calculated adjusted odds ratios. The proportion of young cases (<50 years) was greatest among African Americans (20.8% vs. 8.8%). Higher socioeconomic status, ionizing radiation, formaldehyde, solvents, outdoor work, and animal contact were associated with elevated risk among white men. Physical activity reduced mortality risks among men, although significantly only among whites. Odds ratios for formaldehyde, solvents, benzene, and animal contact were 2.0 or greater among African American women, although not statistically significant. These findings suggest occupational and demographic factors needing further investigation.

Neutron therapy in malignant salivary gland tumors: results at European centers

Malignant salivary gland tumors are relatively rare and account for only 3%-4% of all head and neck cancers. Especially in adenoid cystic carcinoma, the incidence of local recurrence and distant metastases is influenced by the perineural spread of tumor. In advanced salivary gland tumors, surgery alone has a high incidence of local failure. The results of conventional radiotherapy are suboptimal in inoperable or not completely resected salivary gland tumors and in recurrent disease. The pooled data of some international series for low linear energy transfer radiation show a local control of only 28%. Especially in advanced salivary gland tumors, neutron therapy can improve local control. In Europe at least 570 patients with salivary gland tumors have been treated with neutrons alone or with combined modalities. The clinical data of different centers in Europe and the United States result in a similar local control rate of 67% in gross disease. An analysis of different European series shows on average a complication rate of 10.6% for severe radiation-related morbidity. Modern neutron machines and the use of three-dimensional treatment planning systems are now available in a few institutions and may further reduce side effects.

Cancers of the salivary gland: workplace risks among women and men

PURPOSE

The purpose of this study was to assess the risk of salivary gland cancers associated with diverse occupations and industries.

METHODS

A population-based case referent study utilized data obtained from a SEER program cancer registry for cases and by telephone interview for cases and referents to evaluate workplace risks of salivary gland cancer for black and white women and men.

RESULTS

Significantly elevated odds ratios were observed among women employed as hairdressers and those working in beauty shops.

CONCLUSIONS

The risk of salivary gland cancer is elevated among women employed as hairdressers. Further research should assess dyes, sprays, and other inhaled chemicals that may be acting as carcinogens.

Two malignant salivary gland tumours of different type in one patient

The synchronous or metachronous occurrence of two tumours of the salivary glands in one patient is rare. These are mainly benign and of the same histological type. Here we report a 56-year-old man who developed a mucoepidermoid tumour of the left parotid gland four years after diagnosis of adenoid cystic carcinoma of the right submandibular gland. This combination of neoplasms has not to our knowledge been reported before.

Brain and salivary gland tumors related to prior dental radiography: implications for current practice

Five epidemiological studies of brain, cranial meninge, and salivary gland tumor sites reviewed implicate prior dental radiography with increased risk of subtentorial intracranial meningiomas and tumors of the parotid gland. Diagnostic radiography (medical and dental) was the most important risk factor identified for parotid gland cancers; among Los Angeles County residents, about 85% of the cumulative parotid dose from diagnostic radiography came from dental examinations. Irradiation of patients during dental radiography declined substantially from 1920 to 1988; it is uncertain whether current low doses increase risk. Recommendations for exposure reduction are made.

Salivary gland tumors induced by 32P

The oncogenic power of 32P was demonstrated in salivary glands. An intraglandular injection of 0.25 mCi of chromic colloidal phosphate (32P) was administered to young adult Wistar rats. Seven months post-injection, tumors began to appear in the neck region in 64% of the rats. The tumors were sarcomas (50%), carcinomas (35.70%), and carcino-sarcomas (14.28%).

Multiple primary cancers: with reference to atomic bomb survivors in Hiroshima

We treated 44 patients with multiple primary cancers, at the Second Department of Surgery, Hiroshima University, during the 14 year period from 1968-1981. The total number of malignant tumors was 1,934 during this period, thus the incidence of multiple primary cancers was 2.3 per cent. Nine of the 44 were atomic bomb survivors in Hiroshima and were characterized by the frequent incidence of the second tumor about 30 years after exposure to the atomic bomb. In addition, the second tumor tended to develop later in patients prescribed radiotherapy for the first tumor. As for the site of tumor, there was no tendency of more frequent development of tumors in organs highly sensitive to radiation other than the thyroid.

Salivary gland tumors in atomic bomb survivors, hiroshima, japan. II. Pathologic study and supplementary epidemiologic observations

A pathological investigation was undertaken in Hiroshima on cases seen between 1945 and 1971 to determine the relationship between salivary gland tumors and exposure to atomic (A) bomb radiation. Of the 208 cases of histologically confirmed salivary gland tumors, 62 were A-bomb survivors and 146 were nonexposed. The relative risk based on the rate in the nonexposed for malignant tumors of salivary glands among the exposed in Hiroshima Prefecture was 11.0, while that of the submaxillary gland was 13.8 and that of the parotid gland was 9.8. They were all highly significant by X2 test (P less than 0.001). The latent period of malignant salivary gland tumors was shorter in the exposed than in the nonexposed. Four cases of benign salivary gland tumor, all being benign mixed tumors of the parotid gland, were observed in children whose parents had been exposed. The incidence of mixed tumors of the salivary gland among the exposed in Hiroshima City was 2.0 times higher than that among the nonexposed and showed a tendency to increase with proximity to the hypocenter (P less than 0.01).

Second primary malignancies following salivary gland cancers

Four hundred and fifteen males and 367 females who had invasive malignant tumours of the salivary glands as their first cancer diagnosed in Connecticut between 1935 and 1978 were identified and followed 2342 and 2868 person-years respectively. Overall a slight excess of second primary cancers (relative risk 1.35) was observed. Significant excesses were noted for respiratory cancers in males (relative risk 2.8) and for ovarian cancer (relative risk 5.3) but not breast cancer (relative risk 1.3) in women. Possible reasons for excesses at these sites are discussed, but it seems most likely they are related to small number variation.

Two cases of lymphoma of the parotid gland following ablative radioiodine therapy for thyroid carcinoma

Two adult patients are described in whom 131I therapy thyroid carcinoma was followed by the development of non-Hodgkin's lymphoma in salivary glands. Histologically one was lymphocytic and the other histiocytic. The total doses of 131I given were 27 GBq (675 mCi) and 14GBq (350 mCi), lymphoma presenting 10 and 3 years respectively after the initial therapeutic dose of 131I. We suggest that the relationship is a causal one, because of the rarity of salivary gland lymphoma and the high dose or radiation to the salivary glands with this mode of therapy.

Head and neck neoplasia following irradiation for benign conditions

A retrospective review of 143 patients with head or neck tumors who had received radiation therapy in the head and neck area for benign conditions during childhood or adolescence was conducted. This included an analysis of 1,080 patients from the Evanston Hospital Irradiated Thyroid Evaluation Clinic, which was established to define the relationship between irradiation and the subsequent development of thyroid neoplasia. The data support the following concepts of irradiation-induced neoplasia: (1) The thyroid, parathyroid, and salivary glands can develop benign and malignant changes after irradiation for benign conditions, with latent periods averaging about 30 years; (2) Once a glandular abnormality within the irradiated field appears, the risk of other glands in the field developing neoplastic changes is significantly increased.

A neoplastic epithelial duct cell line established from an irradiated human salivary gland

Transformed epithelial cells were isolated by using tissue culture techniques from an irradiated human submandibular salivary gland which showed no neoplastic lesion. These cells, carrying colony-forming ability in semisolid agar, formed a semiconfluent monolayer with occasional tubular arrangement. All transformed clones were demonstrated by electron microscopic examination to be only one type of cells having fine structure similar to intercalated duct cells. Of six clones isolated, one clone with stable growth was cultured within the sponge matrix, resulting in formation of duct-like structure with mucinous eosinophilic substance. Moreover, inoculation of the cloned cells into nude mice resulted in a production of adenocarcinoma with solid and trabecular pattern. These findings indicate that a human intercalated duct cell line carrying tumorigenicity is established from a human submandibular salivary gland with an exposure to irradiation.

Irradiation induced salivary gland neoplasia

Twenty-six patients with a prior history of irradiation for benign conditions of the head and neck and salivary gland abnormalities are reported. All the patients had preoperative physical findings suggestive of tumor, not glandular infection. Forty-six per cent of the patients had one carcinoma and 11% had two carcinomas within the irradiated field. Eight of the 11 malignant tumors in these 26 patients were in the parotid gland. The nonmalignant salivery changes were similar to those previously reported in glands receiving therapeutic irradiation for carcinoma.