The localisation of experimental tumours in scars and healing wounds

Ricerche Sull'Azione Promovente della Follicolina nel Duplice Meccanismo della Carcinogenesi

Studies were undertaken on an eventual initiating or promoting action of follicular hormone in the twofold mechanism of carcinogenesis on the mouse skin. Animals were grouped into two series. The first series was divided into two groups: one was painted with a folliculin oleous solution (Estrene 5) every 3 days, the other with a 5 per cent dilution of croton oil in estrene. The mice of the second series, previously submitted to three paintings with 3:4-benzpyrene, were divided into four groups: 1) control group, 2) painted with Estrene every 3 days, 3) treated with 5 per cent croton oil solution in olive oil, and 4) treated with 5 per cent dilution of croton oil in oleous solution of follicular hormone. Results show that the follicular hormone, either alone or combined with croton oil, fails to produce any initiating and promoting action when painted on mouse skin previously treated with sub-maximal doses of 3:4-benzpyrene. Folliculin, on the contrary, enhances considerably the promoting action of croton oil when painted with it on the skin sensitized with benzpyrene: a rather early appearance of epithelial projections without basal membrane and composed of atypical elements is seen, whereas in animals of the same series, long treated with paintings of croton oil diluted with olive oil or with oleous folliculin this picture is not observed.

MALIGNANCY IN SCARS, CHRONIC ULCERS, AND SINUSES

A collection of 44 cases of malignancy in scars, chronic ulcers, and sinuses, included the following predisposing lesions: a 20-year-old sinus from ischial bursitis, a 23-year-old bed sore, a congenital gumma about 50 years old, three burn scars (average age of scar 56 years), 11 sinuses from chronic osteomyelitis, and 27 chronic ulcers of the leg. The osteomyelitis cases included two rapidly fatal sarcomas, one in a sinus present for 16 years, the other in a 20-year-old sinus. The remaining tumours in this group were squamous carcinomas that developed in sinuses with an average duration of 37 years. In the cases of varicose ulcer, the ulcer had been present on the average for 21 years before the onset of malignancy. One patient in this group, with an ulcer not known to be more than five years old, developed a sarcoma that was fatal in six months. The biopsy diagnosis was difficult in 17 cases, including one of the cases of sarcoma. The difficulty was greatest in cases of osteomyelitis. The conditions discussed are now known as ;Marjolin's ulcer'. In the present series, the degree of malignancy in tumours arising in scars may be low but the malignancy of tumours arising in chronic ulcers and sinuses may be high.

Regeneration and the mechanism of epidermal tumor promotion

Chemically induced epidermal carcinogenesis is often divided into two stages: initiation, which involves the conversion of some epidermal cells into latent neoplastic cells, and promotion, which allows the evolution of this neoplastic change into the formation of a neoplasm. The hallmark of epidermal tumor promotion is the transformation of the normal epidermis into a hyperplastic epidermis. A major unanswered question about epidermal tumor promotion is whether the epidermal hyperplasia that characterizes promoted skin is a regenerative epidermal hyperplasia resulting from damage produced by the promoter. The opinion currently held is that the epidermal hyperplasia produced by tumor promoters is not simply a regenerative epidermal hyperplasia and possesses characteristics which a regenerative hyperplasia does not have, enabling it to evolve into an epidermal neoplasm. The purpose of this review is to present recent evidence which strongly suggests that promoter-induced epidermal hyperplasia is a regenerative hyperplasia. Three principal lines of evidence are reviewed. The first demonstrates that an epidermal regenerative hyperplasia repeatedly produced by wounding or abrasion can promote epidermal carcinogenesis in the initiated skin of mice. The second line of evidence demonstrates that the epidermal hyperplasia produced by the application of 12-O-tetradecanoyl-phorbol-13-acetate (TPA), the most powerful and widely used promoter of skin carcinogenesis, is preceded by damage to the epidermis. This strongly suggests that the epidermal hyperplasia which ensues is a regenerative hyperplasia. Thirdly, evidence is presented which demonstrates that hyperplasia-producing agents which do not promote, produce an epidermal hyperplasia which is different from that produced by tumor promoters. Finally, the review discusses the evidence which suggests that the production of a hyperplasia may be the mechanism for tumor promotion in other organs, such as the liver, bladder, and intestine.

Promotion of epidermal carcinogenesis by repeated damage to mouse skin

Chemically induced epidermal carcinogenesis is usually divided into two stages: initiation, which involves the conversion of some epidermal cells into latent neoplastic cells; and promotion, which results in tumors. The hallmark of chemical promoters is epidermal hyperplasia. The hyperplasia caused by a strong promoter, such as 12-O-tetradecanoylphorbol-13-acetate (TPA), differs morphologically from that caused by weak promoters, such as acetic acid and mezerin. The epidermal regeneration that follows abrasion results in a hyperplastic epidermis that resembles the effects of strong promoters. Repeated mechanical injuries are capable of enhancing papillomas and carcinomas in mouse skin initiated with 7,12-dimethylbenzanthracene (DMBA). Thus, a regenerative epidermal hyperplasia appears to be a precondition for tumor promotion. It is highly probable that many epidermal cells are initiated during the lifetime of man. In the work place, repeated mechanical injury could predispose to epidermal neoplasms.

RICERCHE BIOMETRICHE SULLA CANCEROGENESI CUTANEA. III. AZIONE DELL'OLIO DI CROTON SULL'EPIDERMIDE IRRADIATA CON RAGGI X MOLLI

1) 350 mice of a genetically pure strain were irradiated on the skin with 1000 r of soft X rays. On a half of such animals a treatment with croton oil was undertaken, lasting 3 months; the other half was left without any further treatment. No neoplastic growth was observed.

2) A biometric analysis of the skin at different times has shown a thickening of the epidermis in both sets of animals but with different characters: in the solely irradiated epidermis a swelling of the cytoplasms is observed, whereas in the irradiated and croton-oil treated epidermis an increase of the nuclear bulk (besides the swelling of cytoplasm) and an increase in the number of cells are observed. The increase of the nuclear bulk appears as a rythmic growth.

3) The causes of the lack of the co-carcinogenic effect are discussed.