Gamma rays are another form of photons used in radiotherapy. Gamma rays are produced spontaneously as certain elements (such as radium, uranium, and cobalt 60), which release radiation as they decompose, or decay. Each element decays at a specific rate and gives off energy in the form of gamma rays and other particles. X-rays and gamma rays have the same effect on cancer cells.
Many of the original cobalt gamma ray systems have been replaced with linear accelerators. Cobalt systems can not deliver the higher power radiation that is possible with a linear accelerator, and thus may not be as effective at destroying cancerous tumor. Also, the radiation produced by a linear accelerator can be turned on and off, whereas the cobalt system consists of a radioactive source material which is always on.
Radium was used in various forms until the mid-1900s when cobalt and caesium units came into use. Medical linear accelerators have been used to as sources of radiation since the late 1940s.
http://books.google.com/books?id=hmb...esult#PPA56,M1
see pgs 51-6 in above link
helpful article as discusses history and pluses and minuses of cobalt therapy--on anniversary of 50 yrs of cancer treatment in India--date unknown: mohfw.nic.in/pg87to95.pdf
this implies the first machine was installed in India in 1957 and they are now manufacturing their own--has lots of technical info:
http://www.barc.ernet.in/webpages/le...5/200502-2.pdf.
Cobalt radioisotopes in medicine
Cobalt-60 (Co-60 or 60Co) is a radioactive metal that is used in radiotherapy. It produces two gamma rays with energies of 1.17 MeV and 1.33 MeV. The 60Co source is about 2 cm in diameter and as a result produces a geometric penumbra, making the edge of the radiation field fuzzy. The metal has the unfortunate habit of producing a fine dust, causing problems with radiation protection. Cobalt-60 has a radioactive half-life of 5.27 years. This decrease in activity requires periodic replacement of the sources used in radiotherapy. This is one more reason why cobalt machines have been largely replaced by linear accelerators (linacs) in modern radiation therapy.
this implies the ability of cobalt 60 radiation therapy to give treatment exactly where you want it and minimize treatment where you don't want it is inferior to the abillity of LINAC systems which seems to be why Cobalt machines are considered obsolete in places other than Canada, India, China and the third world--this is just what I have gleaned from reviewing items on Google, There are fine people who are trying to modify it to deliver conformal and IMRT radiation therapy because their machines are limited by it and they seem to be trying to do the best with what they have.
So it seems it seems to be inferior...so the question is... if this is all I can get, should I get it at all.
That would depend on how close your deep margins were to the chest wall (ribs, intercostal muscles) and whether radioisotopes were utilized preop(doesn't sound like it) to determine whether inframammary nodes were sentinel nodes (these are not located in the armpit) By the way, you did not say which quadrant your tumor was in. Inframammary nodes are more often involved in tumors
located in inner quadrants I believe.
THE MOST PERTINENT ARTICLE I FOUND--but again, need to look at details regarding how close your posterior margins were ie, if less than 1-2 mm more worrisome.:
: J Clin Oncol. 2008 Mar 20;26(9):1419-26. Epub 2008 Feb 19. Links
Estrogen receptor, progesterone receptor, HER-2, and response to postmastectomy radiotherapy in high-risk breast cancer: the Danish Breast Cancer Cooperative Group.
Kyndi M, Sørensen FB, Knudsen H, Overgaard M, Nielsen HM, Overgaard J; Danish Breast Cancer Cooperative Group.
Department of Experimental Clinical Oncology, Aarhus University Hospital, Arhus Sygehus, Noerrebrogade 44, Building 5, 2, DK-8000 Aarhus C, Denmark.
kyndi@oncology.dk
PURPOSE: To examine the importance of estrogen receptor (ER), progesterone receptor (PgR), human epidermal growth factor receptor 2 (HER-2), and constructed subtypes in a large study randomly assigning patients to receive or not receive postmastectomy radiotherapy (PMRT). PATIENTS AND METHODS: The present analysis included 1,000 of the 3,083 high-risk breast cancer patients randomly assigned to PMRT in the Danish Breast Cancer Cooperative Group (DBCG) protocol 82 trials b and c. Tissue microarray sections were stained for ER, PgR, and HER-2. Median follow-up time for patients alive was 17 years. End points were locoregional recurrence as isolated first event, distant metastases, and overall survival. For statistical analyses four subgroups were constructed from hormonal receptors (Rec). Rec+ was defined as ER+ and/or PgR+. Rec-as both ER-and PgR-. The four subgroups were Rec+/HER-2-, Rec+/HER-2+, Rec-/HER-2-(triple negative), and Rec-/HER-2+. RESULTS: A significantly improved overall survival after PMRT was seen only among patients characterized by good prognostic markers such as hormonal receptor-positive and HER-2- patients (including the two Rec+ subtypes). No significant overall survival improvement after PMRT was found among patients with an a priori poor prognosis, the hormonal receptor-negative and HER-2+ patients, and in particular the Rec-/HER-2+ subtype. Furthermore, comparing hazard ratios and 95% CIs, significantly smaller improvements in locoregional recurrence control after PMRT were found for ER-and PgR-tumors compared with the ER+ and PgR+ tumors (P = .003 and .04, respectively), and for the triple-negative (P = .02), and the Rec-/HER-2+ subtypes (P = .003) compared with the Rec+/HER-2-subtype. CONCLUSION: Hormonal receptor status, HER-2, and the constructed subtypes may be predictive of locoregional recurrence and survival after postmastectomy radiotherapy.
The next article out of Germany shows they do not find PMRT mandatory except for those with large tumors and/or four or more positive lymph nodes. That is their current standard of care I think, but they did not delineate it by hormonal or her2 status (few articles do)
Strahlenther Onkol. 2008 Jul;184(7):347-53. Links
DEGRO practical guidelines for radiotherapy of breast cancer II. Postmastectomy radiotherapy, irradiation of regional lymphatics, and treatment of locally advanced disease.
Sautter-Bihl ML, Souchon R, Budach W, Sedlmayer F, Feyer P, Harms W, Haase W, Dunst J, Wenz F, Sauer R.
Municipal Hospital Karlsruhe, Karlsruhe, Germany.
strahlentherapie@klinikum-karlsruhe.de
BACKGROUND AND PURPOSE: The aim of the present paper is to update the practical guidelines for radiotherapy of breast cancer published in 2006 by the breast cancer expert panel of the German Society for Radiooncology (DEGRO). These recommendations were complementing the S3 guidelines of the German Cancer Society (DKG) elaborated in 2004. The present DEGRO recommendations are based on a revision of the DKG guidelines provided by an interdisciplinary panel and published in February 2008. METHODS: The DEGRO expert panel (authors of the present manuscript) performed a comprehensive survey of the literature. Data from lately published meta-analyses, recent randomized trials and guidelines of international breast cancer societies, yielding new aspects compared to 2006, provided the basis for defining recommendations referring to the criteria of evidence-based medicine. In addition to the more general statements of the DKG, this paper emphasizes specific radiooncologic issues relating to radiotherapy after mastectomy (PMRT), locally advanced disease, irradiation of the lymphatic pathways, and sequencing of local and systemic treatment. Technique, targeting, and dose are described in detail. RESULTS: PMRT significantly reduces local recurrence rates in patients with T3/T4 tumors and/or positive axillary lymph nodes (12.9% with and 40.6% without PMRT in patients with four or more positive nodes). The more local control is improved, the more substantially it translates into increased survival. In node-positive women the absolute reduction in 15-year breast cancer mortality is 5.4%. Data referring to the benefit of lymphatic irradiation are conflicting. However, radiotherapy of the supraclavicular area is recommended when four or more nodes are positive and otherwise considered individually. Evidence concerning timing and sequencing of local and systemic treatment is sparse; therefore, treatment decisions should depend on the dominating risk of recurrence. CONCLUSION: There is common consensus that PMRT is mandatory for patients with T3/T4 tumors and/or four or more positive axillary nodes and should be considered for patients with one to three involved nodes. Irradiation of the lymphatic pathways and the optimal time point for onset of radiotherapy are still under debate.
YOU DID NOT LIST YOUR PATHOLOGY ie, ductal vs lobular vs inflammatory but here is an article (obviously her2 status is not listed, but I have not found it listed in the articles I have reviewed so far)
Radiother Oncol. 2008 Oct 22. [Epub ahead of print] Links
The impact of postmastectomy radiotherapy on local control in patients with invasive lobular breast cancer.
Diepenmaat LA, Sangen MJ, Poll-Franse LV, Beek MW, Berlo CL, Luiten EJ, Nieuwenhuijzen GA, Voogd AC.
Faculty of Health Medicine and Life Sciences, Maastricht University, Maastricht, The Netherlands.
PURPOSE: The aim of this population-based study was to examine the impact of postmastectomy radiotherapy on the risk of local recurrence in patients with invasive lobular breast cancer (ILC). METHODS: The population-based Eindhoven Cancer Registry was used to select all patients with ILC, who underwent mastectomy in five general hospitals in the southern part of the Netherlands between 1995 and 2002. Of the 499 patients 383 patients fulfilled the eligibility criteria. Of these patients, 170 (44.4%) had received postmastectomy radiotherapy. The median follow-up was 7.2 years. Fourteen patients (3.7%) were lost to follow-up. RESULTS: During follow-up 22 patients developed a local recurrence, of whom 4 had received postmastectomy radiotherapy. The 5-year actuarial risk of local recurrence was 2.1% for the patients with and 8.7% for the patients without postmastectomy radiotherapy. After adjustment for age at diagnosis, tumour stage and adjuvant systemic treatment, the patients who underwent postmastectomy radiotherapy were found to have a more than 3 times lower risk of local recurrence compared to the patients without (Hazard Ratio 0.30; 95% Confidence Interval: 0.10-0.89). CONCLUSION: Local control is excellent for patients with ILC who undergo postmastectomy radiotherapy and significantly better than for patients not receiving radiotherapy.
The letter to the editor, which cites the original article, discusses PMRT being necessary in those with 4 or more axillary nodes vs 1 or more nodes, but noone discusses it being necessary in those w no nodes:
http://jco.ascopubs.org/cgi/content/full/26/13/2075
Here is a very helpful article for you, although your tumor was not as big as these and so at even less risk:*****
: Cancer. 2008 Jul 1;113(1):38-47. Links
Postmastectomy radiation therapy for lymph node-negative, locally advanced breast cancer after modified radical mastectomy: analysis of the NCI Surveillance, Epidemiology, and End Results database.
Yu JB, Wilson LD, Dasgupta T, Castrucci WA, Weidhaas JB.
Department of Therapeutic Radiology, Yale School of Medicine, New Haven, CT 06520, USA.
james.b.yu@yale.edu
BACKGROUND: The role of postmastectomy radiotherapy (PMRT) for lymph node-negative locally advanced breast carcinoma (T3N0M0) after modified radical mastectomy (MRM) with regard to improvement in survival remains an area of controversy. METHODS: The 1973-2004 National Cancer Institute (NCI) Surveillance, Epidemiology, and End Results (SEER) database was examined for patients with T3N0M0 ductal, lobular, or mixed ductal and lobular carcinoma of the breast who underwent MRM, treated from 1988-2003. Patients who were men, who had positive lymph nodes, who survived < or =6 months, for whom breast cancer was not the first malignancy, who had nonbeam radiation, intraoperative or preoperative radiation were excluded. The average treatment effect of PMRT on mortality was estimated with a propensity score case-matched analysis. RESULTS: In all, 1777 patients were identified; 568 (32%) patients received PMRT. Median tumor size was 6.3 cm. The median number of lymph nodes examined was 14 (range, 1-49). Propensity score matched case-control analysis showed no improvement in overall survival with the delivery of PMRT in this group. Older patients, patients with ER- disease (compared with ER+), and patients with high-grade tumors (compared with well differentiated) had increased mortality. CONCLUSIONS: The use of PMRT for T3N0M0 breast carcinoma after MRM is not associated with an increase in overall survival. It was not possible to analyze local control in this study given the limitations of the SEER database. The impact of potential improvement in local control as it relates to overall survival should be the subject of further investigation. (Copyright) 2008 American Cancer Society.
You also didn't state your age:
Int J Radiat Oncol Biol Phys. 2008 May 1;71(1):98-106. Epub 2007 Nov 8. Links
Use of postmastectomy radiotherapy in older women.
Smith BD, Haffty BG, Smith GL, Hurria A, Buchholz TA, Gross CP.
Radiation Oncology Flight, Wilford Hall Medical Center, Lackland Air Force Base, TX, USA.
benjamin.smith@lacland.af.mil
PURPOSE: Clinical trials and guidelines published between 1997 and 2001 concluded that postmastectomy radiotherapy (PMRT) improves overall survival for women with high-risk breast cancer. However, the effect of these findings on current practice is not known. Using the Surveillance, Epidemiology, and End Results-Medicare cohort, we sought to characterize the adoption of PMRT from 1992 to 2002 and identify risk factors for PMRT omission among high-risk older patients. METHODS AND MATERIALS: We identified 28,973 women aged > or =66 years who had been treated with mastectomy for invasive breast cancer between 1992 and 2002. Trends in the adoption of PMRT for low- (T1-T2N0), intermediate- (T1-T2N1), and high- (T3-T4 and/or N2-N3) risk patients were characterized using a Monte Carlo permutation algorithm. Multivariate logistic regression identified the risk factors for PMRT omission and calculated the adjusted use rates. RESULTS: Postmastectomy radiotherapy use increased gradually and consistently for low-risk (+2.16%/y) and intermediate-risk (+7.20%/y) patients throughout the study interval. In contrast, PMRT use for high-risk patients increased sharply between 1996 and 1997 (+30.99%/y), but subsequently stabilized. Between 1998 and 2002, only 53% of high-risk patients received PMRT. The risk factors for PMRT omission included advanced age, moderate to severe comorbidity, smaller tumor size, fewer positive lymph nodes, and geographic region, with adjusted use rates ranging from 63.5% in San Francisco to 44.9% in Connecticut. CONCLUSION: Among the high-risk patients, PMRT use increased sharply in 1997 after the initial clinical trial publication. Despite subsequent guidelines recommending the use of PMRT, no further increase in PMRT use has occurred, and nearly 50% of high-risk patients still do not receive PMRT.
J BUON. 2007 Apr-Jun;12(2):215-20.Links
Postmastectomy radiotherapy in intermediate risk stage I-II breast cancer patients.
Mladenovic J, Susnjar S, Gavrilovic D, Borojevic N.
Department of Radiotherapy, Institute for Oncology and Radiology of Serbia, Belgrade, Serbia.
mladenovicj@ncrc.ac.yu
PURPOSE: To evaluate the correlation of postmastectomy radiotherapy (PMRT) with local relapse rate, disease-free survival (DFS) and overall survival (OS) in a group of breast cancer (BC) patients at intermediate risk for locoregional relapse (stage I-II with either 1-3 positive axillary nodes, or node-negative grade III BC) treated with radical mastectomy. PATIENTS AND METHODS: We evaluated 482 stage I-II BC patients, with either node-negative grade 3 tumors or with 1-3 positive nodes irrespective of tumor grade, treated with radical mastectomy at our Institute from 1986 to 1994. After mastectomy they received either adjuvant CMF (cyclophosphamide, methotrexate, 5-fluorouracil) chemotherapy (N=172), or adjuvant endocrine therapy (N=310). Postoperative radiotherapy (RT group) to the regional lymph nodes with tumor dose (TD) 48 Gy in 22 fractions was delivered to 199 patients. RESULTS: After a median follow-up of 79.5 months, no difference in relapse rate between the two groups was seen (30.6% in the RT group vs. 36.7% in the no RT group; x(2), p=0.1). Local recurrence rate occurring alone or with distant metastases was 4.52% in the RT group vs. 7.77% in the no RT group (x(2), p=0.1). However, local recurrence rate alone was significantly higher in the RT group compared to the no RT group (2.01 vs. 6.01%, x(2), p=0.041). In premenopausal patients local relapses occurred in 3.2% of patients with postoperative RT and in 8.2% in patients without RT (Fisher's exact test, p=0.48). Non significant difference was registered in postmenopausal patients with (4.76%) or without RT (6.58%). Ten-year DFS and OS were 53.5% and 68.7% in the RT group vs. 52.9% and 75.2% in the no RT group (non significant difference). CONCLUSION: Our results did not show that PMRT significantly influences the incidence of disease relapse, DFS and OS in stage I-II BC patients with intermediate risk for disease relapse. However, it seems that PMRT might influence the occurrence of locoregional recurrence in these patients.
PMID: 17600875