Early studies with orthovoltage radiotherapy demonstrated an approximate two-third decrease in risk of local recurrence of breast cancer without overall survival benefit.
Postmastectomy radiation can reduce moderate to high risk patients to a low risk patient for loco-regional recurrence.
Increases cure rates for subgroups with substantial risks of local-regional recurrence.
Postmastectomy radiation can reduce locoregional recurrence risk for clinically stage III disease, T3 tumors of high-grade, or for four or more positive lymph nodes, with adjuvant or neoadjuvant chemotherapy.
Meta-analyses of late 1980s to 1990s studies revealed an approximate two-third reduction in the risk of local breast cancer recurrence, an improved mortality from breast cancer but a transiently decreased overall survival from deaths caused by problems other than breast cancer.
Advantages of postmastectomy radiation counteracted by increased non-breast cancer deaths, especially from cardiovascular deaths in patients over the age of 60 years.
Local regional recurrence rate increases with increasing tumor size and the number of lymph nodes involved.
Local regional recurrence rate for patients with tumors 5 cm or smaller and with fewer than 4 involved lymph nodes is estimated to be less than 15% with a potential reduction to less than 5% with the addition of postmastectomy radiation therapy and an overall 3-4% benefit in overall survival.
In patients with four or more involved lymph nodes risk of local recurrence is nearly 30% and there is a two-third reduction in the rate of loco-regional recurrence with the use of postmastectomy radiation with a 9-10% benefit in overall survival.
Chest wall failures at 10 years are observed in more than 20-30% of patients with at least 4 axillary metastatic axillary nodes, node positive T3,diseas, inflammatory breast cancer and/or residual axillary metastasis following neoadjuvant chemotherapy.
Postmastectomy radiation can reduce the above rates by more than 50%, and is recommended routinely in these cases.
Benefits of postmastectomy RT are less well defined in T1/T2 breast cancer associated with 1-3 positive axillary nodes.
Patients with 1-3 positive lymph nodes treated with adjuvant chemotherapy experience modest rates of local regional recurrence and such treatment must be given consideration although controversy still exists as to its benefits.
Postmastectomy radiation is considered for patients with breast cancer is 5 cm or smaller and 1-3 positive nodes.
Radiation isn’t given routinely after mastectomy, but some women benefit from it:
are larger than 5 cm
have spread to four or more lymph nodes
have positive margins
have spread to the skin
For patients with breast cancer and one to three positive lymph nodes: Some studies found that radiation improved survival, while other studies showed no benefits.
Recent meta-analysis shows that women diagnosed with early-stage breast cancer with only one to three positive lymph nodes are less likely to have a recurrence and more likely to survive breast cancer if they have radiation after mastectomy (European Breast Cancer Conference).
In these studies all the women had mastectomy to remove early-stage breast cancer and then were randomly assigned to get radiation therapy or not after surgery.
In the women with no cancer in the lymph nodes, radiation after mastectomy didn’t reduce the risk of recurrence and didn’t improve survival rates.
In women with breast cancer in one to three nodes, radiation after mastectomy:
reduced the risk of recurrence by 32%
improved survival rates by 20% compared to not getting radiation after mastectomy.
Looking at the results in a different way, radiation therapy after mastectomy in women with early-stage breast cancer in one to three lymph nodes led to almost 12 fewer breast cancer recurrences per 100 women after 10 years and eight fewer deaths per 100 women after 20 years.
These benefits were the same for women who had breast cancer in one lymph node and women who had breast cancer in two or three lymph nodes.
It also didn’t matter if the women were in studies that prescribed chemotherapy or hormonal therapy after surgery:
In women with breast cancer in four or more lymph nodes, radiation after mastectomy:
reduced the risk of recurrence by 21%
improved survival rates by 13% compared to not getting radiation therapy.
In other words, radiation therapy after mastectomy in women with early-stage breast cancer in four or more lymph nodes led to nine fewer breast cancer recurrences per 100 women after 10 years and nine fewer deaths per 100 women after 20 years.
The standard of care is for women with early-stage breast cancer in four or more lymph nodes to get radiation after mastectomy.
Postmastectomy radiation is strongly recommended for tumors greater than 5 cm or four or more positive lymph nodes.
Increases the risk of complications and poor cosmetic results after breast reconstruction.
Immediate reconstruction limits technical approaches for the delivery of post mastectomy radiation, potentially resulting in increased heart and lung doses.
Increasingly common for new breast reconstruction to be treated with post mastectomy radiation.
The use of PRMT and breast reconstruction have increased in the recent past, despite deleterious interactions.
The use of a scar boost following post mastectomy radiation decreases the absolute percentage of local recurrence is in patients with high risk features, but does not increase recurrence free survival.
Chest wall radiation therapy after mastectomy refers to the use of external beam radiation to the ipsilateral chest wall including the mastectomy scar and, when indicated, drain sites, as part of postmastectomy radiation therapy (PMRT) for breast cancer.
The primary goal is to reduce the risk of locoregional recurrence and improve survival, especially in patients with node-positive disease or other high-risk features.
Most local regional occurrences occur in the chest wall, so this area is considered to be a critical target for post mastectomy radiotherapy.
PMRT typically includes not only the chest wall but also regional lymphatics (such as the supraclavicular, axillary, and sometimes internal mammary nodes) when indicated.
Guidelines recommend chest wall irradiation for most patients with positive axillary nodes, select node-negative patients with high-risk features, and those with locally advanced disease after neoadjuvant therapy.
Mastectomy it standandard of care for more than 1/3 of patients with stage I and stage II breast cancer.
Stage II disease involves tumors, no more than 5 cm in diameter with metastases to 1-3 axillary lymph nodes (N1) or tumors of at least 2 cm without nodal metastases stages T1N1M0, T2N1M0, and T3N0M0, in the TNM classification.
PatienTS with stage II breast cancer with N1 disease or have N0 disease, but with poor histologic features are considered to be intermediate risk for recurrence.
Previous studies with what is now considered sub optimal adjuvant therapy reported that post mastectomy radiotherapy for a stages II and III reduced the risk of local regional recurrence and improved 10 year survival among women with nodal metastases.
Chest wall radiation therapy after mastectomy is a core component of PMRT, targeting the chest wall and often regional nodes to reduce recurrence and improve outcomes in appropriately selected breast cancer patients.
In the SUPREMO trial 10 year survival after post mastectomy chestwall radiation in breast cancer patients classified as PN1 with involvement of 1 to 3 three nodes or PnO pathologically node negative with additional risk factors treated with mastectomy and contemporary adjuvant systemic therapy did not result in higher overall survival than no chest radiation among these intermediate risk patients with early breast cancer.
Major improvement, systemic therapy and reduction in breast cancer mortality challenge the applicability of the evidence base for postmastectomy radiotherapy in current practice.