A wide range of treatments are available to treat stage I and II BCCs, ranging from excision, Mohs micrographic surgery, radiation, electrodesiccation and curettage, photodynamic therapy, and topical 5-fluorouracil, or imiquimod. These therapies have differing cure rates, modes of delivery, and side effects that factor into selecting the best treatment for the older adult. Randomized studies with cure rates compared to excision, adapted from the National Cancer Institute 2014, are presented in Table 1. Recent data from Australia showed that excision rate was highest for keratinocytic cancers in men aged 75–84 years, and that excision rates declined for individuals less than 45 years [10].

Topical pharmacotherapy for skin cancer is a consideration for individuals who decline or cannot undergo surgical procedures. Topical 5-fluorouracil (5-FU) 5 % and imiquimod 5 % are FDA approved for small superficial BCCs. While level 1 evidence (according to the Oxford 2011 Levels of Evidence) exists for topical imiquimod use in superficial BCC, only level 2 evidence for topical 5-FU exists for superficial BCC. The largest study to date for 5FU and superficial BCC is a 31-patient study in which 90 % clearance rate was achieved after 11 weeks of twice-daily treatment, with average follow-up time of only 3 weeks [11]. Evidence for 5FU against nodular BCC is level 4 only [12]. Imiquimod has demonstrated utility against superficial and nodular BCC (level 1 and 2 evidence, respectively), with histologic cure rates exceeding 70 % and optimal treatment results balancing efficacy with tolerability at five applications per week [12]. Nevertheless, follow-up times are limited to 12 weeks or less, and further study is needed to document long-term cure rates [13–17]. More recently, ingenol mebutate has demonstrated level 2 evidence against superficial BCCs [12]. Because of the limited number of studies and short follow-up times in the studies, these topical therapies are generally considered only when patients decline or cannot undergo surgical treatments.

Self-applied topical therapies such as 5-fluorouracil or imiquimod may be difficult for older adults if they are not in readily visible areas or manual dexterity or memory is a potential concern for adherence. A caregiver may be enlisted to assist with self-applied topical therapies, with written instructions and areas of treatment outlined. Because of the lower rate of cure for topical field therapies compared to excision or Mohs the ability to follow up in clinic for skin cancer surveillance is essential when considering this modality.

Recent data from a large European multicenter randomized controlled trial of photodynamic therapy (MAL-PDT) versus topical imiquimod versus topical fluorouracil for superficial BCCs demonstrated that imiquimod was superior to MAL-PDT, and that topical 5FU was non-inferior at 12-month follow-up [18]. The average age of patients in each arm ranged from 62 to 64 years old. Cure rates at 12 months were 93 % for imiquimod (regimen was 5 days a week for 6 weeks), 91 % for fluorouracil (regimen was twice a day for 4 weeks), and 87 % for MAL-PDT (3-h incubation under occlusion ×2 treatments).

Electrodesiccation and curettage can result in 5-year cure rates of 82–94 % for BCCs; however in one large study up to 15 % of patients experienced hypertrophic scars [19, 20]. More recent data on quality-of-life outcomes of treatments for cutaneous BCC and SCC in individuals with mean age over 65 showed that patients who underwent electrodesiccation and curettage report lower quality of life compared to excision or Mohs surgery [21].

Cryotherapy monotherapy has been considered in individuals with BCC often as a treatment only when no other good choices are available. For instance, recent case reports in older individuals illustrate their potential utility [22]. However, good-quality data in superficial BCCs has been reported in randomized studies compared head to head with MALA PDT (3-h incubation up to three sessions), and found to have similar recurrence rates at 5 years (up to two treatments, each with two freeze-thaw cycles) but inferior cosmetic results [23].

Recently, retrospective data from 631 BCCs treated with superficial radiation therapy has been reported. This modality utilizes ionizing radiation, or electronic surface brachytherapy, which consists of low-energy photon X-rays. These treatments are being used increasingly by dermatologists, in conjunction with radiation oncologists. Compared to traditional radiation therapy, SRT and eSBT consist of fewer treatments and can be delivered in the outpatient setting without a linear accelerator. Aggregate data from superficial and nodular BCCs 5 years after treatment revealed a recurrence rate of 4.2 % [24]. Higher recurrence rates occurred in tumors greater than 2 cm. Cosmetic outcomes have not been addressed, particularly in head-to-head comparison with other treatment modalities. While superficial radiation therapy may be considered in individuals who cannot or will not undergo surgical treatment or topical pharmacotherapy, concerns about costs of superficial radiation therapy, risk of radiation dermatitis, and secondary cancers remain to be studied further.

One of the largest recent breakthroughs in skin cancer therapy over the past 5 years is the commercial availability of smoothened inhibitors, a targeted way to disrupt the Hedgehog signaling pathway in advanced basal cell carcinomas. In the largest multicenter clinical study to date of targeted therapy for advanced basal cell carcinoma (unresectable or metastatic), 119 patients with an average age of 62 years demonstrated a 46.4 % response rate [25] after a median of 5.5 months of vismodegib exposure. When this data was broken down by age greater or equal to 65 years versus less than or equal to 65 years [26] there was no significant difference in the overall response rate by age. There did not appear to be significant differences in frequency of side effects either. However, in those under 65 years, the percentage of individuals with grade 3 or higher side effects was 2 % in those aged 65 or less compared to 11 % in those aged 65 or greater, suggesting that the severity of side effects in adults aged 65 or older may be greater than those under 65. Future larger studies may identify covariates that might explain the increased severity in adverse events in older adults.

Like stage I and II BCCs, the gold standard therapy for stage I and II cutaneous squamous cell carcinoma (CSCC) continues to be excision, offering the highest cure rates [27]. In one pooled average of 12 studies (n = 1,144) the local recurrence rate after excision was 5.4 % and in a pooled average of 10 studies (n = 1,572) the local recurrence rate after Mohs micrographic surgery was 3.0 % [27]. For CSCCs with two or more high-risk features (such as size, depth of invasion, perineural spread, location on the lip or ear) adjuvant radiation after excision can be considered. For SCCs with perineural invasion treated with adjuvant radiotherapy, pooled local recurrence average based on five studies (n = 22) was 18.2 %, and for SCCs without perineural invasion, pooled local recurrence average based on four studies was 11.1 % [27].

For patients with invasive CSCC who cannot tolerate surgery or decline surgery, a number of treatment options exist, although the cure rates are much lower and close follow-up monitoring for recurrence is required. For instance, in one small study of 26 patients with face and neck CSCC who had declined surgery or experienced treatment failure after surgery, photodynamic therapy with red light led to complete response rate of 77 % at 48 months [28]. Due to the small study, delineation of clinical or histologic characteristics most likely to result in cure is unclear. However, other data on photodynamic therapy indicates high recurrence rates after apparent initial response that averaged 26.4 % (n = 119) [27]. Other treatment modalities in the literature include curettage and electrodesiccation of SCCs (generally less than 2 cm), in seven studies and variable follow-up periods, with indicated recurrence average of 1.7 % (n = 1,131). For cryotherapy, the recurrence average was 0.8 % based on eight studies (n = 273) for low-risk SCCs less than 2 cm [27].

For small invasive CSCCs, another modality that has seen increasing use in the older population is superficial X-ray therapy (SXRT). While the published short-term response rates are high, with only 1.8 % recurrence at 2 years and 5.8 % recurrence at 5 years for SXRT in one study with 994 SCC patients [24], issues urgently needing study include which sites are most amenable to treatment, characteristics of “low-risk” SCCs that make SRT a good choice, cost-benefit considerations due to significant cost of SRT, optimal number of treatments, and risk of long-term secondary cancers. In one retrospective study of superficial radiation treatment for 180 large cutaneous SCCs (mean age late 60s) in Switzerland, relapse-free survival was 95 % after 1 year and 80 % after 10 years [29], with the anatomic location showing the highest relapse-free survival as around the eyes and on the cheek.

For SCC in situ (SCCIS), excision still confers the highest cure rate although topical therapies can be a good choice, with the same caveats in the elderly population as discussed above. There is level II evidence for the use of topical imiquimod (5 % daily × 16 weeks) for SCCIS, with randomized study showing resolution of 73 % of SCCIS at 9 months [12, 30]. The use of topical 5-fluorouracil (one to two times daily, up to two cycles of 4 and 6 weeks) and ALA photodynamic therapy (4-h incubation) for SCCIS is based on level 4 evidence with 12-month response rates reported at 82 % and 48 %, respectively [12, 31].