Preventive Strikes: Women, Precancer, and Prophylactic Surgery

Conclusion: Uncertainty

Conclusion: Uncertainty
The Wassermann Reaction: Screening for an Older “Dread Disease” Preventive treatment of precancerous lesions is a twentieth-century innovation. Three developments favored the rise of this approach: (a) the transformation of cancer into a “pathologists’ disease” in the 1910s and 1920s; (b) the introduction of mass screening for malignancies, which started in the 1940s with exfoliate cytology but expanded greatly in the 1970s and 1980s; and (c) the introduction, from the 1950s on, of population-based thinking to oncology and its consequence , the search for elements that increase cancer risk. This progression occurred in all the developed nations but took distinct forms and followed a different pace. In some cases, such as the diffusion of the Pap smear, divergent pathways—the intervention of a major cancer charity in the United States, an alliance between activists and politicians in the United Kingdom, development internal to the medical profession in France—produced a similar result: the generalization of screening for cervical cancer. In other cases, such as diagnosis and treatment of proliferative lesions of the breast, different local and national medical cultures generated divergent professional responses. Nevertheless, in spite of variability of practices, physicians who strived to diagnose and treat precancerous lesions faced a similar problem everywhere: the difficulty of correlating the presence of these lesions with the clinical disease of cancer. The desire to transform precancer into a stable diagnostic category can be compared with earlier efforts to stabilize a diagnosis of another “dread disease,” with deep social and cultural resonances: the history of the Wassermann reaction for the detection of syphilis.In the early twentieth century,syphilis was often perceived as a diagnostic puzzle. The proteiform manifestations of late syphilis were often confounded with other diseases: neurological disorders, bone and muscle ailments, malignant tumors, or cardiovascular pathologies. This difficulty, syphilis experts hoped, would disappear thanks to the development of a blood test— the Wassermann reaction—that detects the underlying cause of all the clinical manifestations of syphilis: an infection with the bacillus Treponema pallidum. Unfortunately, the blood test was problematic. First believed to display speci- fic anti-Treponema antibodies, this test was redefined in the 1910s as revealing poorly understood “changes in syphilis blood” and the presence of a mysterious “Wassermann reagin.” A strong aspiration to develop a diagnostic test for syphilis stimulated, however, a collective effort to adapt the Wassermann reaction to uses in the clinics. Scientists tinkered with this test until they obtained reproducible results. In the 1920s, experts viewed the link between positive Wassermann reactions and the infection by Treponema pallidum as a well-established scientific fact.1 Serologists and clinicians who employed the Wassermann test in the 1920s and 1930s did not fully understand its scientific basis. They were persuaded nevertheless that when performed by competent laboratory workers, the test rarely produced false positive results. Only people infected with Treponema tested positive. Accordingly, a positive result of “Wassermann serology” was seen as a sufficient reason to start treatment with antisyphilitic drugs and to expose patients to the toxicity of these compounds. At first, the Wassermann test was used only to confirm a suspicion of infection with Treponema. In the late 1930s increased confidence in the reliability of this test favored the introduction of mass screening for syphilis in large segments of the general population: people about to get married, pregnant women, newly recruited soldiers. The compilation of results of screening campaigns revealed unsuspected discrepancies between epidemiological and serological data. The Wassermann reaction was calibrated for high specificity (low tolerance of false positive results) and lower sensitivity (higher tolerance of false negative results) to avoid disastrous social consequences of an erroneous diagnosis of a shameful disease. Mass screening was therefore expected to underevaluate the prevalence of syphilis. Just the opposite was established : the percentage of positive results in tested populations was higher than the percentage expected on the basis of epidemiological data. The Wassermann reaction , the experts had found in the late 1940s, was considerably less specific than initially believed.2 A positive Wassermann reaction, previously interpreted as a sure sign of an infection with Treponema pallidum, was transformed into an indication of a potential presence of a wide range of pathologies.3 The history of the Wassermann reaction illustrates conditions that favor the diffusion of diagnostic approaches grounded in an imperfect knowledge: Exis226 Preventive Strikes tence...