As we have seen above, the recognition of the fact that a series of successive changes take place in carcinogenesis has invalidated the concept that in order to consider a substance active in this field, it has to induce the entire series of changes by itself, including the passage into the phase of invasive cancer. An agent can be considered active if it induces only a part of the successive series of changes. Didactically, we can thus consider changes concerning the subnuclear, nuclear, cellular and metazoic levels. We have investigated the intervention of lipids in carcinogenesis from this specific point of view.

The coordination of data from various observations and experiments has indicated that some of the lipids would act especially at the cellular and tissue levels.

Statistical data have indicated a greater proportion of cancer of the cervix in non Jewish women as compared to Jewish women. This was tentatively related to the circumcision of the respective males and this correlation was confirmed by statistical data concerning other groups of population practicing circumcision, such as the Moslems. The probable role of smegma was seen in experiments in animals made by different workers. It was reported that in mice, smegma, sterilized or non sterilized, introduced in the vagina of mice followed by the suture of the vagina, would induce papilomatous and cancerous lesions of the cervix.

Statistical studies (324) showed a similar correlation between cancer of the prostate and circumcision, with a lower proportion of cancer in circumcised individuals than in those not circumcised. Entirely different results were obtained by other workers. Studies made by the group of Memorial Hospital in Cleveland, concerning cancer in situ, showed no differences between Jewish and non Jewish women. Similarly, several workers have reported that the prostates in individuals over 40 years of age, who died of conditions other than cancer, have present in high proportion cancer in situ cells. No correlation with circumcision could be found in these cases, the same proportion being found in all the ethnic groups examined. (325)

We tried to interpret these totally discordant conclusions of the two groups of statistics and found the explanation in the concept of plural intervention of carcinogens. In the first group of statistics in the cases of both females and males, the cancerous processes considered were those in the invasive cellular stage, while in the second group of statistics, the noninvasive cancer phase was considered. It appears thus quite clear that the intervention of the circumcision and respectively of the smegma exists but has to be placed at a precise point in the progressive changes in the evolution of the cancerous condition, at the passage from noninvasive into invasive cancer. Without any influence upon the appearance of the cancer in situ, the smegma would act manifestly by changing the proportion of active cancer present. Its influence appears thus to be exerted at the cellular level, where the occurring changes result in the passage of the noninvasive into the invasive cancer, and at the tissue level where the loss of the capacity to defend itself against the cancer cells permits their invasion. This led us to the hypothesis that the cancerous process in the cervix and prostate, evolves independently of circumcision until the cancer in situ step, but will make the next step toward invasive cancer predominantly under the influence of the smegma of noncircumcised males. Without such intervention at this stage, such a change may occur but in an impressively lower proportion. The invasive cancer of the cervix is thus almost entirely non existent in virgin nuns. This consideration and the richness of smegma in positive lipids has permitted us to go farther and consider the problem of the role played by these lipids in carcinogenesis.

We have tried for a long time, but with litle success, to induce cancer in animals through the administration of unsaponifiable fractions alone. The several positive cases obtained in mice with repeated injections of the unsaponifiable fractions of placenta, chicken embryos, eggs or butter, have not appeared sufficiently consistent to warrant any conclusions.

In our attempt to investigate an intervention of the positive lipids for the specific change, corresponding to the passage of the noninvasive to the invasive cancer, we carried out the following experiment. We selected female mice with at least two previous pregnancies. After a third pregnancy, when in lactation, the mammary gland was injected with small amounts of the above mentioned unsaponifiable fractions. The results seem to indicate a higher proportion of mammary carcinoma in these mice than in controls.

Similarly, we have tried to influence cells of the cervix in mice, through the introduction of the same different preparations of unsaponifiable fractions in the vagina of ex breeder mice, followed by suture of the vagina. The first results have shown a high proportion of malignant tumors. The concept of the intervention of abnormal lipids in carcinogenesis has led us to utilize in similar experiments, instead of the above preparations, unsaponifiable fractions considered to be heterogenized by being heated above 320°C. At the moment, these experiments which are in progress seem to indicate the existence of such an influence.

It is of even greater interest to note the influence exerted by the unsaponifiable fractions upon animals that had received urethane, according to the experiments of Berenblum. By combining three factors, urethane for the first changes in the amino acids, several pregnancies for the changes until the noninvasive phase and unsaponifiable fractions especially heterogenized for the passage into the invasive phase, a high proportion of invasive mammary and cervical cancers seems to be induced in the first experiments. Of importance appears the factor that a certain lapse of time is necessary between each two factors which are applied in the above mentioned succession. This concords with the concept of plural successive changes in carcinogenesis discussed above.

Carcinogenic Activity Of Urethane

The interesting research of Berenblum has brought an important contribution not only for the largely debated role of urethane as carcinogen, but also for the problem of carcinogenesis in general. The fact that croton oil, applied to the skin, induces the appearance of malignant tumors in animals previously fed with urethane, concords largely with the concept of plural changes taking place in carcinogenesis. The analysis of the influence exerted by carbamic acid upon amino acids would place the intervention of this agent at the first members of the biological realm. It can thus be seen that the bond between the amino acid group and the carboxyl and amine groups of carbamic acid occur in a way similar to that which occurs between two amino acids with the big difference that in the first case it would result in the appearance of the CNCN formation. (Fig. 201) As mentioned above, this CNCN formation represents the group which characterizes the first biological entity. The place of this CNCN group, not at the end of the molecule opposed to the carboxyl as in the alkaline amino acids, but as corresponding to the bond which results in polymers, represents the anomaly, which according to the work hypothesis we advance, would correspond to the first cancerous entity. The fact that the specific activity of urethane takes place at the lowest levels of organization, explains the necessity that a certain time separates its intervention from that of croton oil, which would act only at the higher levels, probably inducing the passage from noninvasive to invasive phase. This time is necessary for the first cancerous changes to build up the series of cancerous hierarchic entities since the cocarcinogen, croton oil, would act only in those more evolved cancerous entities. In experiments in progress, the passage of the urethane induced noninvasive cancerous entities into invasive cancer, is successfully obtained by treatment with preparations of unsaponifiable fractions of placenta or eggs.