The answer to the title of this Part 1 is in two parts. First, we know of no intrinsic relationship at all between scoliosis and breast-cancer. The second part is that for decades the management of scoliosis was done with frequent x-ray checks of the spine, in the worst possible way for breast irradiation. This led some of the women to develop breast-cancer from the radiation, not from the scoliosis. We shall be discussing some of the opportunities missed (for decades) to prevent such breast-cancer, and some of the elegant work done later to prevent many of the breast-cancers arising from the management of scoliosis.
Scoliosis --- What Is It?
Scoliosis is defined (from the Greek scolios, for curved) as a lateral curvature of the spine. There are several possible bases for lateral curvature of the spine, but there is one common entity which concerns us here. That is the entity known as Idiopathic Scoliosis or Habitual Scoliosis. The appellation, "idiopathic," simply means that the cause is unknown. Professor Arthur Steindler, Head of Orthopedic Surgery at Iowa State University, wrote the chapter on " Static Deformities of the Spine" in the 1942 Edition of Christopher's Surgery.
He wrote at p.463-464:
"The So-Called Habitual Scoliosis or Idiopathic Scoliosis: This term merely indicates the absence of a definite underlying cause. It implies a general or constitutional predisposition, such as anatomical build and general habitus, or inherited or acquired weakness or relaxation of the spine and its musculature ... The majority of cases occur in females." And (at p.466):
"So-called habitual or idiopathic scoliosis has always received considerable attention from the viewpoint of prophylaxis. It has been called `school scoliosis' because it is believed to develop during the school age; some investigators have found as high as 20 to 30 % of all school children afflicted with this `functional' scoliosis as a result of faulty posture. However, the usual prophylactic measures are, as a rule, belated. The critical age is betwen the third and fifth year, and it is at this time that prophylaxis should be practiced." (Recent investigators cite a later age-band for this disorder.)
The Early History of Treatment
From Dr. Steindler's discussion, it is clear he did not feel muscle training, external or internal splinting were too helpful. External splinting meant braces and internal splinting meant operative fusion of the spine. He certainly was not optimistic about the management of scoliosis. We quote his final conclusions (p. 469):
"This short outline of the treatment serves to emphasize the all-importance of the earliest possible recognition and timely prophylaxis of scoliosis. Until these vital facts have become generally appreciated, there is not likely to be any real progress in the management of cases of scoliosis."
Unfortunately --- during the months and years of the efforts to correct the scoliosis by braces, by casts, by musculature training --- the physicians continued to monitor the patients both with physical examination and with x-ray examinations of the spine. Most unfortunately, the method of taking the spine films in the early period was to have the beam enter the front of the body, and exit through the back (the anteroposterior, or AP, approach). From the point of view of breast irradiation, this was the worst possible approach for part of the x-ray examination. The lateral views which were taken were unfavorable but not as unfavorable as the antero-posterior view.
Apparently very little concern was shown for the steady accumulation of breast-dose from the repeated spinal exams, taken in this extremely unfavorable AP view.
So now the long-drawn out management procedures for scoliosis meant a seriously growing radiation dose to the breasts of adolescent and post-adolescent girls and young women. There was no comment whatever in the Steindler chapter about any hazard of the radiographic aspect of management. We did not expect to find any. The times were such that broadly, the medical profession did not believe that diagnostic x-rays spread over 3 to 6 years could be harmful. Let us be clear; this was a belief, not a demonstration.
A decade later, approximately, the 1950 Edition of Mitchell-Nelson Textbook of Pediatrics, 5th Edition, has the Orthopedic Pediatrics Chapter written by Dr. Charles C. Chapple. In his brief section on "Scoliosis," the part on Treatment in no way mentions the repeated x-rays associated with management of the disorder:
"Treatment. Nutritional improvement and postural exercises are usually sufficient in the treatment of mild cases, but in the more severe ones, since the scoliosis is liable to become more marked with increasing muscular development, correction by such orthopedic means as exercise and supporting devices is advisable in addition to the treatment of any underlying factor. Many require spinal fusion."
No mention is made of the numerous x-rays which accompanied the use of such corrective devices as braces or casts.
Two decades later, in 1968, Ambulatory Pediatrics edited by Dr. Morris Green and Dr. Robert Haggerty, commented succinctly on scoliosis as follows:
"Although complex, carefully fitted bracing may occasionally prevent progression of the deformity, there is increasing evidence that early spinal fusion is by far the most effective method of treatment. Complete correction of the curve is rarely possible, and the purpose of fusion is to stabilize the spine and prevent progression."
There is no mention whatever about the numerous spine films which were taken in the course of such management of scoliosis. Quite obviously the textbooks over three decades, at least, did not consider it worth mentioning that the many spine films were giving a very high dose to the breasts, and that such dosage was really unnecessary.
Finally, in 1979, there was a massive change in the tide.
Part 2. A Spectacular Achievement in Dose Reduction for Scoliosis Patients
Nash, Gregg, Brown, and Pillai (1979), all at Case Western Reserve University, called attention to the serious problem of excessive radiation dosage accumulated by female scoliosis patients during the course of one of the disorder's common treatments, known as the Milwaukee Brace treatment. As Nash and co-workers pointed out, adolescent girls would be monitored with some 20 x-ray films, plus retakes, or a total of 22 radiographs during the average three-year treatment period. Most films were taken as AP shots. Having made their own measurements, Nash and co-workers estimated an average entrance dose of 1.13 roentgens for the AP shots used, and 1.78 roentgens for the lateral shots. From their estimates of dose to organs, they concluded (p.371) that "given an average of twenty-two roentgenograms over a three-year Milwaukee Brace-treatment program," the risk of breast-cancer due to x-ray radiation rose "from 140 to 290 per million (110 percent)."
Even worse than the conclusion of Nash and co-workers that the monitoring of scoliosis therapy was more than doubling the patient's risk of later breast-cancer, was their additional conclusion that "many scoliosis patients may require more roentgenograms than the average scoliosis patient postulated in this study."
Since these types of therapy had been going on before Steindler's writings in 1942, there is good reason to consider that the entire 1920-1960 period was characterized by this sort of therapy for scoliosis.
Details of the Steps Which Reduced Breast-Dose
Nash and colleagues decided to do something about this situation. They proved in a series of scoliosis patients that shifting beam direction from anterior-posterior to posterior-anterior could reduce the breast-cancer risk by a factor of 28 ! As for the image quality, the Nash team reported that the x-ray films obtained from the PA beam direction proved technically satisfactory for routine scoliosis care.
Additional work of real merit on reducing the risk from x-rays for scoliosis patients has been done by Gray, Hoffman, and Peterson at the Mayo Clinic. In an extensive study (1983), they report on how they used the following combination of measures to reduce dose:
- A posterior-anterior beam direction;
- Specially designed leaded acrylic filters;
- A high-speed screen-film system;
- A breast-shield;
- Additional filtration in the x-ray tube collimator.
Dr. Gray and co-workers reported at page 5 that the following reductions in breast dose occurred:
"...For the breasts there was a sixty-nine fold reduction from 344 to less than five milliroentgens for the postero-anterior radiograph and fifty-five fold reduction from 277 to less than five milliroentgens for the lateral radiograph."
Part 3. Determining (1920-1960) Breast-Doses in Scoliosis Management
Hoffman, Lonstein, Morin and co-workers (1989) have conducted a followup study of a series of women who had multiple diagnostic x-rays in the course of scoliosis management. We shall make use of some of their data to provide entries for the Master Table, Column H.
They regard scoliosis as a relatively common condition. The prevalence in the general population has been estimated to be as high as 8 %. However, a major determinant of the prevalence reported is the degree of spine curvature used to diagnose scoliosis. The disease is more prevalent in women than in men. Hoffman and co-workers provide the following [not totally consistent with their estimate above of prevalence of the disorder]:
"Adolescent idiopathic scoliosis afflicts nearly 2 % of the U.S. population, and school jurisdictions in over 50% of the United States have screening programs for children 9-14 years of age. Girls require treatment more often than boys. Once detected, scoliosis requires periodic x-ray monitoring of the spine, especially during adolescence, when the bones are growing at an accelerated rate. The times of breast development and menarche are clinically important because they indicate that the growth spurt has begun or will begin soon. Patients commonly receive anteroposterior and lateral spinal x-rays to monitor the progression of spinal curvature and the effect of treatment."
These school programs certainly are addressing an older group than that suggested worth studying in the Steindler paper, which suggested the critical age to be between the third and fifth year.
We shall use the breast-dose estimates provided by Hoffman et al. in this study (1989).
- Item 1:
This study was done in Hennepin County, in the State of
Minnesota. The study population consisted of 1,030 women with a
confirmed diagnosis of scoliosis or kyphosis who were seen in one
of three hospitals or in one clinic in Minneapolis-St.Paul,
Minnesota area. We were not given any assurance that this study
included all the cases of scoliosis being treated in Hennepin
County during the period under investigation. It is possible that
such inclusion existed, but since we do not know, we caution the
reader that breast-exposure estimated nationally from these data
may well be an underestimate because of the absence of an unknown
fraction of the total number of cases.
- Item 2:
The 1,030 women who qualified for inclusion were
followed up for 26 years, on average.
- Item 3:
The estimate of dose to the breasts was a mean value of
12.8 total rads (medical rads), acquired over a period of 8.7
years, on average. The examinations were given in the period, 1935
to 1965.
- Item 4:
Since the acquisition of cases occurred over a period
of 30 years (1935 -1965), the number of acquistions per year in
Hennepin County must have been, on average, 1,030 / 30, or 34.3
cases per year.
- Item 5:
Since the average age at diagnosis was 12.3 years, we
should assign some of the cases to age groups below 12.3 years and
some to age groups above 12.3 years. We shall arbitrarily estimate
the distribution of the annual 34.3 cases as in the following
tabulation.